Lesson 16.2: Elapsed Time and Duration Calculations
Applied concepts and practical problem solving for Elapsed Time and Duration Calculations.
⏱️ Reading Time: 20 mins
• ❓ 50 Interactive Practice Questions
🌟
Real-Life Story: Time and Clocks
Film Festival Cinema: Scheduling feature movies and cleaning intermissions.
💡 Core Mathematical Concepts: Elapsed Time and Duration Calculations
Focus areas: Calculating time passed between start and finish across hour boundaries..
| Concept / Term | Mathematical Meaning | Real-Life Application |
|---|---|---|
| Elapsed Time | End Time minus Start Time | Time taken for an event |
| Bridging the Hour | Counting minutes to the next whole hour first, then adding hours and remaining minutes | 09:40 to 11:15: 20m to 10:00 + 1h + 15m = 1h 35m |
| Adding Time Durations | If minutes exceed 60, convert 60 minutes into 1 additional hour | 45 min + 35 min = 80 min = 1h 20m |
📝 Step-by-Step Worked Examples
Worked Example 1: Find duration from 10:25 to 13:10
10:25 to 11:00 (35m) + 2 hours to 13:00 + 10m to 13:10 = 2 hours 45 minutes.
Worked Example 2: Add 2h 45m to 14:30
14:30 + 2h = 16:30; 16:30 + 45m = 17:15.
⚠️ Common Misconceptions to Avoid
Common Misconception: Treating minutes like decimals (base 10)
Correction: 1 hour has 60 minutes, not 100 minutes! 2.5 hours is 2 hours 30 minutes, not 2 hours 50 minutes.
Common Misconception: Subtracting minutes directly when borrowing
Correction: Borrowing 1 hour adds 60 minutes, NOT 100 minutes.
🎯
Self-Check Challenge
A theatrical play begins at 07:15 PM and lasts for 2 hours and 50 minutes. At what time does the play finish?
Answer & Explanation:
07:15 PM + 2 hours = 09:15 PM. 09:15 PM + 50 minutes = 10:05 PM.
🎯 Key Learning Takeaways
Extend understanding of Elapsed Time and Duration Calculations.
Solve multi-step real-world problems systematically.
Verify solutions through mathematical reasoning.
📄 Printable Worksheets (5 Available)
Download ready-to-print PDFs for offline student practice with separate parent/teacher answer keys.
G5-M-CH16-WS05
A4 • 15 Qs
Time and Clocks: Worksheet 5
Practice Assessment 5 • Central Botanical Gardens Context
G5-M-CH16-WS04
A4 • 15 Qs
Time and Clocks: Worksheet 4
Practice Assessment 4 • Eco-Friendly Solar Park Context
G5-M-CH16-WS03
A4 • 15 Qs
Time and Clocks: Worksheet 3
Practice Assessment 3 • Harbor Marine Terminal Context
G5-M-CH16-WS02
A4 • 15 Qs
Time and Clocks: Worksheet 2
Practice Assessment 2 • Science & Discovery Museum Context
G5-M-CH16-WS01
A4 • 15 Qs
Time and Clocks: Worksheet 1
Practice Assessment 1 • City Regional Airport Context
✍️ Lesson Practice Questions (50 Questions)
Solve these real-world challenges online, test your understanding, and reveal instant step-by-step explanations.
1
Short Answer
Hard
2 Marks
A digital stopwatch displays 3,745 seconds. Express this duration in hours, minutes, and seconds.
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
1 hour, 2 minutes, 25 seconds
Step-by-Step Explanation:
3,745 ÷ 3,600 = 1 hour remainder 145 seconds. 145 ÷ 60 = 2 minutes remainder 25 seconds. Result: 1 h 2 min 25 s.
2
Short Answer
Hard
2 Marks
A flight departs Dubai at 02:30 (Dubai time) and lands in London after a 7-hour and 45-minute flight. If London is 4 hours behind Dubai, what local time does the flight arrive in London?
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
06:15
Step-by-Step Explanation:
Departure = 02:30 Dubai. Flight duration = 7 h 45 min -> arrival at 10:15 Dubai time. London is 4 hours behind: 10:15 - 4 hours = 06:15 London time.
3
Short Answer
Hard
2 Marks
How does the 24-hour clock eliminate ambiguity compared to the 12-hour AM/PM clock in international aviation schedules?
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
In 24-hour time, every moment in a day has a unique 4-digit number (e.g. 08:00 vs 20:00), preventing critical scheduling errors caused by mixing up AM and PM.
Step-by-Step Explanation:
Unique monotonic hour numbers eliminate typographical and verbal AM/PM confusion.
4
Short Answer
Hard
2 Marks
Explain why minutes and seconds are based on multiples of 60 (sexagesimal) rather than 10 (decimal).
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
Historical astronomers in ancient Mesopotamia used base-60 because 60 is divisible by 2, 3, 4, 5, 6, 10, 12, 15, 20, and 30, making fractional divisions of time exceptionally simple.
Step-by-Step Explanation:
Base-60 offers superior fractional divisibility without recurring decimals.
5
Short Answer
Medium
1 Mark
A student calculates the difference between 3:50 PM and 5:10 PM as 2 hours 40 minutes by subtracting 3:50 from 5:10 directly. What is the correct elapsed time?
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
1 hour 20 minutes
Step-by-Step Explanation:
Hours and minutes use base-60, not base-10. 3:50 to 4:00 is 10 min; 4:00 to 5:10 is 1 h 10 min. Total = 1 h 20 min.
6
Short Answer
Medium
1 Mark
Emma says: '12:00 in the middle of the night is 12:00 PM.' Identify Emma's error and state the correct 12-hour and 24-hour designations.
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
12:00 AM (or 00:00)
Step-by-Step Explanation:
Midnight is 12:00 AM (00:00 in 24-hour time). Noon is 12:00 PM.
7
Fill in the Blanks
Medium
1 Mark
Fill in the elapsed time: Start = 09:20, End = 11:05, Elapsed = [ ? ] minutes.
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
105
Step-by-Step Explanation:
1 hour 45 minutes = 60 + 45 = 105 minutes.
8
Fill in the Blanks
Medium
1 Mark
Complete the time conversion: 300 seconds = [ ? ] minutes.
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
5
Step-by-Step Explanation:
300 ÷ 60 = 5 minutes.
9
Short Answer
Medium
1 Mark
A satellite broadcast begins at 19:50 and lasts for 1 hour and 40 minutes. At what 24-hour time does the broadcast end?
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
21:30
Step-by-Step Explanation:
19:50 + 10 min = 20:00. Remaining time = 1 h 30 min. 20:00 + 1 h 30 min = 21:30.
10
Short Answer
Medium
1 Mark
An express passenger train departs from Central Station at 10:45 AM and arrives at Coastal Terminal at 2:20 PM. How long was the train journey?
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
3 hours 35 minutes
Step-by-Step Explanation:
10:45 AM to 1:45 PM is 3 hours. 1:45 PM to 2:20 PM is 35 minutes. Total = 3 hours 35 minutes.
11
Short Answer
Medium
1 Mark
At the Central Botanical Gardens, an engineering shift begins at 08:30 and concludes at 17:15. If workers take a 45-minute lunch break, how many net hours and minutes did they work?
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
8 hours
Step-by-Step Explanation:
Total elapsed time = 8 hours 45 minutes. Deduct 45-minute lunch break: 8 hours net working time.
12
Multiple Choice
Easy
1 Mark
A film starts at 14:10 and ends at 16:35. What is the running time of the film?
A
2 hours 25 minutes
B
2 hours 15 minutes
C
1 hour 55 minutes
D
2 hours 35 minutes
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
2 hours 25 minutes
Step-by-Step Explanation:
From 14:10 to 16:10 is 2 hours. From 16:10 to 16:35 is 25 minutes. Total = 2 h 25 min.
13
Multiple Choice
Easy
1 Mark
How many minutes are in 3 hours and 25 minutes?
A
205 minutes
B
185 minutes
C
225 minutes
D
195 minutes
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
205 minutes
Step-by-Step Explanation:
(3 × 60 = 180) + 25 = 205 minutes.
14
Multiple Choice
Easy
1 Mark
Convert 21:15 in 24-hour format into 12-hour AM/PM format.
A
9:15 PM
B
9:15 AM
C
11:15 PM
D
8:15 PM
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
9:15 PM
Step-by-Step Explanation:
Subtract 12 from 21: 21 - 12 = 9. So 9:15 PM.
15
Multiple Choice
Easy
1 Mark
Convert 4:45 PM into 24-hour clock time.
A
16:45
B
14:45
C
04:45
D
18:45
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
16:45
Step-by-Step Explanation:
For PM times after noon, add 12 to the hour: 4 + 12 = 16. So 16:45.
16
Short Answer
Hard
2 Marks
A digital stopwatch displays 3,745 seconds. Express this duration in hours, minutes, and seconds.
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
1 hour, 2 minutes, 25 seconds
Step-by-Step Explanation:
3,745 ÷ 3,600 = 1 hour remainder 145 seconds. 145 ÷ 60 = 2 minutes remainder 25 seconds. Result: 1 h 2 min 25 s.
17
Short Answer
Hard
2 Marks
A flight departs Dubai at 02:30 (Dubai time) and lands in London after a 7-hour and 45-minute flight. If London is 4 hours behind Dubai, what local time does the flight arrive in London?
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
06:15
Step-by-Step Explanation:
Departure = 02:30 Dubai. Flight duration = 7 h 45 min -> arrival at 10:15 Dubai time. London is 4 hours behind: 10:15 - 4 hours = 06:15 London time.
18
Short Answer
Hard
2 Marks
How does the 24-hour clock eliminate ambiguity compared to the 12-hour AM/PM clock in international aviation schedules?
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
In 24-hour time, every moment in a day has a unique 4-digit number (e.g. 08:00 vs 20:00), preventing critical scheduling errors caused by mixing up AM and PM.
Step-by-Step Explanation:
Unique monotonic hour numbers eliminate typographical and verbal AM/PM confusion.
19
Short Answer
Hard
2 Marks
Explain why minutes and seconds are based on multiples of 60 (sexagesimal) rather than 10 (decimal).
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
Historical astronomers in ancient Mesopotamia used base-60 because 60 is divisible by 2, 3, 4, 5, 6, 10, 12, 15, 20, and 30, making fractional divisions of time exceptionally simple.
Step-by-Step Explanation:
Base-60 offers superior fractional divisibility without recurring decimals.
20
Short Answer
Medium
1 Mark
A student calculates the difference between 3:50 PM and 5:10 PM as 2 hours 40 minutes by subtracting 3:50 from 5:10 directly. What is the correct elapsed time?
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
1 hour 20 minutes
Step-by-Step Explanation:
Hours and minutes use base-60, not base-10. 3:50 to 4:00 is 10 min; 4:00 to 5:10 is 1 h 10 min. Total = 1 h 20 min.
21
Short Answer
Medium
1 Mark
Emma says: '12:00 in the middle of the night is 12:00 PM.' Identify Emma's error and state the correct 12-hour and 24-hour designations.
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
12:00 AM (or 00:00)
Step-by-Step Explanation:
Midnight is 12:00 AM (00:00 in 24-hour time). Noon is 12:00 PM.
22
Fill in the Blanks
Medium
1 Mark
Fill in the elapsed time: Start = 09:20, End = 11:05, Elapsed = [ ? ] minutes.
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
105
Step-by-Step Explanation:
1 hour 45 minutes = 60 + 45 = 105 minutes.
23
Fill in the Blanks
Medium
1 Mark
Complete the time conversion: 300 seconds = [ ? ] minutes.
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
5
Step-by-Step Explanation:
300 ÷ 60 = 5 minutes.
24
Short Answer
Medium
1 Mark
A satellite broadcast begins at 19:50 and lasts for 1 hour and 40 minutes. At what 24-hour time does the broadcast end?
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
21:30
Step-by-Step Explanation:
19:50 + 10 min = 20:00. Remaining time = 1 h 30 min. 20:00 + 1 h 30 min = 21:30.
25
Short Answer
Medium
1 Mark
An express passenger train departs from Central Station at 10:45 AM and arrives at Coastal Terminal at 2:20 PM. How long was the train journey?
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
3 hours 35 minutes
Step-by-Step Explanation:
10:45 AM to 1:45 PM is 3 hours. 1:45 PM to 2:20 PM is 35 minutes. Total = 3 hours 35 minutes.
26
Short Answer
Medium
1 Mark
At the Eco-Friendly Solar Park, an engineering shift begins at 08:30 and concludes at 17:15. If workers take a 45-minute lunch break, how many net hours and minutes did they work?
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
8 hours
Step-by-Step Explanation:
Total elapsed time = 8 hours 45 minutes. Deduct 45-minute lunch break: 8 hours net working time.
27
Multiple Choice
Easy
1 Mark
A film starts at 14:10 and ends at 16:35. What is the running time of the film?
A
2 hours 25 minutes
B
2 hours 15 minutes
C
1 hour 55 minutes
D
2 hours 35 minutes
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
2 hours 25 minutes
Step-by-Step Explanation:
From 14:10 to 16:10 is 2 hours. From 16:10 to 16:35 is 25 minutes. Total = 2 h 25 min.
28
Multiple Choice
Easy
1 Mark
How many minutes are in 3 hours and 25 minutes?
A
205 minutes
B
185 minutes
C
225 minutes
D
195 minutes
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
205 minutes
Step-by-Step Explanation:
(3 × 60 = 180) + 25 = 205 minutes.
29
Multiple Choice
Easy
1 Mark
Convert 21:15 in 24-hour format into 12-hour AM/PM format.
A
9:15 PM
B
9:15 AM
C
11:15 PM
D
8:15 PM
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
9:15 PM
Step-by-Step Explanation:
Subtract 12 from 21: 21 - 12 = 9. So 9:15 PM.
30
Multiple Choice
Easy
1 Mark
Convert 4:45 PM into 24-hour clock time.
A
16:45
B
14:45
C
04:45
D
18:45
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
16:45
Step-by-Step Explanation:
For PM times after noon, add 12 to the hour: 4 + 12 = 16. So 16:45.
31
Short Answer
Hard
2 Marks
A digital stopwatch displays 3,745 seconds. Express this duration in hours, minutes, and seconds.
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
1 hour, 2 minutes, 25 seconds
Step-by-Step Explanation:
3,745 ÷ 3,600 = 1 hour remainder 145 seconds. 145 ÷ 60 = 2 minutes remainder 25 seconds. Result: 1 h 2 min 25 s.
32
Short Answer
Hard
2 Marks
A flight departs Dubai at 02:30 (Dubai time) and lands in London after a 7-hour and 45-minute flight. If London is 4 hours behind Dubai, what local time does the flight arrive in London?
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
06:15
Step-by-Step Explanation:
Departure = 02:30 Dubai. Flight duration = 7 h 45 min -> arrival at 10:15 Dubai time. London is 4 hours behind: 10:15 - 4 hours = 06:15 London time.
33
Short Answer
Hard
2 Marks
How does the 24-hour clock eliminate ambiguity compared to the 12-hour AM/PM clock in international aviation schedules?
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
In 24-hour time, every moment in a day has a unique 4-digit number (e.g. 08:00 vs 20:00), preventing critical scheduling errors caused by mixing up AM and PM.
Step-by-Step Explanation:
Unique monotonic hour numbers eliminate typographical and verbal AM/PM confusion.
34
Short Answer
Hard
2 Marks
Explain why minutes and seconds are based on multiples of 60 (sexagesimal) rather than 10 (decimal).
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
Historical astronomers in ancient Mesopotamia used base-60 because 60 is divisible by 2, 3, 4, 5, 6, 10, 12, 15, 20, and 30, making fractional divisions of time exceptionally simple.
Step-by-Step Explanation:
Base-60 offers superior fractional divisibility without recurring decimals.
35
Short Answer
Medium
1 Mark
A student calculates the difference between 3:50 PM and 5:10 PM as 2 hours 40 minutes by subtracting 3:50 from 5:10 directly. What is the correct elapsed time?
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
1 hour 20 minutes
Step-by-Step Explanation:
Hours and minutes use base-60, not base-10. 3:50 to 4:00 is 10 min; 4:00 to 5:10 is 1 h 10 min. Total = 1 h 20 min.
36
Short Answer
Medium
1 Mark
Emma says: '12:00 in the middle of the night is 12:00 PM.' Identify Emma's error and state the correct 12-hour and 24-hour designations.
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
12:00 AM (or 00:00)
Step-by-Step Explanation:
Midnight is 12:00 AM (00:00 in 24-hour time). Noon is 12:00 PM.
37
Fill in the Blanks
Medium
1 Mark
Fill in the elapsed time: Start = 09:20, End = 11:05, Elapsed = [ ? ] minutes.
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
105
Step-by-Step Explanation:
1 hour 45 minutes = 60 + 45 = 105 minutes.
38
Fill in the Blanks
Medium
1 Mark
Complete the time conversion: 300 seconds = [ ? ] minutes.
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
5
Step-by-Step Explanation:
300 ÷ 60 = 5 minutes.
39
Short Answer
Medium
1 Mark
A satellite broadcast begins at 19:50 and lasts for 1 hour and 40 minutes. At what 24-hour time does the broadcast end?
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
21:30
Step-by-Step Explanation:
19:50 + 10 min = 20:00. Remaining time = 1 h 30 min. 20:00 + 1 h 30 min = 21:30.
40
Short Answer
Medium
1 Mark
An express passenger train departs from Central Station at 10:45 AM and arrives at Coastal Terminal at 2:20 PM. How long was the train journey?
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
3 hours 35 minutes
Step-by-Step Explanation:
10:45 AM to 1:45 PM is 3 hours. 1:45 PM to 2:20 PM is 35 minutes. Total = 3 hours 35 minutes.
41
Short Answer
Medium
1 Mark
At the Harbor Marine Terminal, an engineering shift begins at 08:30 and concludes at 17:15. If workers take a 45-minute lunch break, how many net hours and minutes did they work?
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
8 hours
Step-by-Step Explanation:
Total elapsed time = 8 hours 45 minutes. Deduct 45-minute lunch break: 8 hours net working time.
42
Multiple Choice
Easy
1 Mark
A film starts at 14:10 and ends at 16:35. What is the running time of the film?
A
2 hours 25 minutes
B
2 hours 15 minutes
C
1 hour 55 minutes
D
2 hours 35 minutes
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
2 hours 25 minutes
Step-by-Step Explanation:
From 14:10 to 16:10 is 2 hours. From 16:10 to 16:35 is 25 minutes. Total = 2 h 25 min.
43
Multiple Choice
Easy
1 Mark
How many minutes are in 3 hours and 25 minutes?
A
205 minutes
B
185 minutes
C
225 minutes
D
195 minutes
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
205 minutes
Step-by-Step Explanation:
(3 × 60 = 180) + 25 = 205 minutes.
44
Multiple Choice
Easy
1 Mark
Convert 21:15 in 24-hour format into 12-hour AM/PM format.
A
9:15 PM
B
9:15 AM
C
11:15 PM
D
8:15 PM
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
9:15 PM
Step-by-Step Explanation:
Subtract 12 from 21: 21 - 12 = 9. So 9:15 PM.
45
Multiple Choice
Easy
1 Mark
Convert 4:45 PM into 24-hour clock time.
A
16:45
B
14:45
C
04:45
D
18:45
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
16:45
Step-by-Step Explanation:
For PM times after noon, add 12 to the hour: 4 + 12 = 16. So 16:45.
46
Short Answer
Hard
2 Marks
A digital stopwatch displays 3,745 seconds. Express this duration in hours, minutes, and seconds.
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
1 hour, 2 minutes, 25 seconds
Step-by-Step Explanation:
3,745 ÷ 3,600 = 1 hour remainder 145 seconds. 145 ÷ 60 = 2 minutes remainder 25 seconds. Result: 1 h 2 min 25 s.
47
Short Answer
Hard
2 Marks
A flight departs Dubai at 02:30 (Dubai time) and lands in London after a 7-hour and 45-minute flight. If London is 4 hours behind Dubai, what local time does the flight arrive in London?
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
06:15
Step-by-Step Explanation:
Departure = 02:30 Dubai. Flight duration = 7 h 45 min -> arrival at 10:15 Dubai time. London is 4 hours behind: 10:15 - 4 hours = 06:15 London time.
48
Short Answer
Hard
2 Marks
How does the 24-hour clock eliminate ambiguity compared to the 12-hour AM/PM clock in international aviation schedules?
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
In 24-hour time, every moment in a day has a unique 4-digit number (e.g. 08:00 vs 20:00), preventing critical scheduling errors caused by mixing up AM and PM.
Step-by-Step Explanation:
Unique monotonic hour numbers eliminate typographical and verbal AM/PM confusion.
49
Short Answer
Hard
2 Marks
Explain why minutes and seconds are based on multiples of 60 (sexagesimal) rather than 10 (decimal).
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
Historical astronomers in ancient Mesopotamia used base-60 because 60 is divisible by 2, 3, 4, 5, 6, 10, 12, 15, 20, and 30, making fractional divisions of time exceptionally simple.
Step-by-Step Explanation:
Base-60 offers superior fractional divisibility without recurring decimals.
50
Short Answer
Medium
1 Mark
A student calculates the difference between 3:50 PM and 5:10 PM as 2 hours 40 minutes by subtracting 3:50 from 5:10 directly. What is the correct elapsed time?
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
1 hour 20 minutes
Step-by-Step Explanation:
Hours and minutes use base-60, not base-10. 3:50 to 4:00 is 10 min; 4:00 to 5:10 is 1 h 10 min. Total = 1 h 20 min.