Basics
• In time-related questions, you will need to calculate how much time has passed.
• In many of these questions, you will need to break up time and add the sum of its parts.
• To answer a question involving different time zones, you will need to adjust the departure time to coincide with the arrival time zone.
• The calculator may or may not come into play with these questions.
Question
How much time has passed between 9:45 AM and 4:15 PM? Express your answer in hours and minutes.
Answer
6 hours 30 minutes
Answer Process
9:45 AM – 10:00 AM = 15 minutes
10:00 AM – 12:00 PM (Noon) = 2 hours
12:00 PM – 4:00 PM = 4 hours
4:00 PM – 4:15 PM = 15 minutes
Time = 15 minutes + 2 hours + 4 hours + 15 minutes = 6 hours 30 minutes
Question
With reference to the question above, express your answer in hours as a mixed number.
Answer
hours
Answer Process
9:45 AM – 10:00 AM = 15 minutes
10:00 AM – 12:00 PM (Noon) = 2 hours
12:00 PM – 4:00 PM = 4 hours
4:00 PM – 4:15 PM = 15 minutes
Time = 15 minutes + 2 hours + 4 hours + 15 minutes = 6 hours 30 minutes
Convert 30 minutes to a fraction of an hour: =
hour
Time = hours
Input | Display | Comment |
![]() |
blinker | clears screen |
![]() ![]() ![]() |
ratio of 30 minutes to 60 minutes per hour |
|
![]() |
30 minutes converted to |
|
Time |
Question
With reference to the question above, express your answer in hours in decimal form.
Answer
6.5 hours
Answer Process
9:45 AM – 10:00 AM = 15 minutes
10:00 AM – 12:00 PM (Noon) = 2 hours
12:00 PM – 4:00 PM = 4 hours
4:00 PM – 4:15 PM = 15 minutes
Time = 15 minutes + 2 hours + 4 hours + 15 minutes = 6 hours 30 minutes
Convert 30 minutes to a fraction of an hour: =
hour
Convert hour to a decimal:
hour = 1 ÷ 2 = 0.5 hour
Time = 6.5 hours
Input | Display | Comment |
![]() |
blinker | clears screen |
![]() ![]() ![]() |
ratio of 30 minutes to 60 minutes per hour |
|
![]() |
30 minutes converted to |
|
![]() |
0.5 | (Toggle) |
Time |
Question
How much time has passed between 9:15 AM and 4:45 PM? Express your answer in hours and minutes.
Answer
7 hours 30 minutes
Answer Process
9:15 AM – 10:00 AM = 45 minutes
10:00 AM – 12:00 PM (Noon) = 2 hours
12:00 PM – 4:00 PM = 4 hours
4:00 PM – 4:45 PM = 45 minutes
Time = 45 minutes + 2 hours + 4 hours + 45 minutes =
6 hours 90 minutes = 7 hours 30 minutes
Question
A plane departs from New York City at 8:00 AM Eastern Standard Time (EST) and arrives in Los Angeles at 11:00 AM Pacific Standard Time (PST). How many hours did the flight take?
Answer
6 hours
Answer Process
Adjust the departure time to coincide with the arrival time zone.
Departure: 8:00 AM EST = 5:00 AM PST
Arrival: 11:00 AM PST
5:00 AM PST —> 11:00 AM PST = 6 hours
Question
A plane departs from Chicago at 6:00 AM Central Standard Time (CST) and arrives in Miami at 10:00 AM Eastern Standard Time (EST). How many hours did the flight take?
Answer
3 hours
Answer Process
Adjust the departure time to coincide with the arrival time zone.
Departure: 6:00 AM CST = 7:00 AM EST
Arrival: 10:00 AM EST
7:00 AM EST —> 10:00 AM EST = 3 hours
Practice – Questions
1. How much time has passed between 7:45 AM and 3:30 PM? Express your answer in hours and minutes.
2. With reference to Question 1, express your answer in hours as a mixed number.
3. With reference to Question 1, express your answer in hours in decimal form.
4. How much time has passed between 7:45 AM and 3:55 PM? Express your answer in hours and minutes.
5. How much time has passed between 5:45 PM and 2:30 AM? Express your answer in hours and minutes.
6. How much time has passed between 5:15 PM and 2:55 AM? Express your answer in hours and minutes.
7. A plane departs from New York City at 7:00 AM Eastern Standard Time (EST) and arrives in Los Angeles at 10:00 AM Pacific Standard Time (PST). How many hours did the flight take?
8. A jet departs from New York City at 1:00 PM Eastern Standard Time (EST) and arrives in Los Angeles at 11:00 AM Pacific Standard Time (PST). How many hours did the flight take?
9. A plane departs from Denver at 10:00 AM Mountain Standard Time (MST) and arrives in Boston at 4:00 PM Eastern Standard Time (EST). How many hours did the flight take?
10. A jet departs from Denver at 10:00 AM Mountain Standard Time (MST) and arrives in Boston at 1:00 PM Eastern Standard Time (EST). How many hours did the flight take?
Practice – Answers
1. 7 hours 45 minutes
2. hours
3. 7.75 hours
4. 8 hours 10 minutes
5. 8 hours 45 minutes
6. 9 hours 40 minutes
7. 6 hours
8. 1 hour
9. 4 hours
10. 1 hour