Mathematics
Grade 8
15 min
Elapsed time word problem
Elapsed time word problem
Tutorial Preview
1
Introduction & Learning Objectives
Learning Objectives
Identify the start time, end time, and duration in a given word problem.
Calculate the elapsed time between two given points in time.
Determine the end time when given a start time and a duration.
Determine the start time when given an end time and a duration.
Solve multi-step elapsed time problems involving different units (hours, minutes, days).
Utilize visual aids such as number lines or T-charts to model and solve elapsed time problems.
Convert between 12-hour (AM/PM) and 24-hour time formats as needed for calculations.
Ever wondered how long that epic movie marathon lasted, or how much time you spent on your favorite game? 🎮 Calculating elapsed time helps us track our day!
In this lesson, you'll learn how to break down and solve word problem...
2
Key Concepts & Vocabulary
TermDefinitionExample
Elapsed TimeThe amount of time that has passed between a start time and an end time.If a movie starts at 7:00 PM and ends at 9:30 PM, the elapsed time is 2 hours and 30 minutes.
Start TimeThe specific point in time when an event or activity begins.If you begin studying at 4:15 PM, 4:15 PM is the start time.
End TimeThe specific point in time when an event or activity concludes.If your class finishes at 10:50 AM, 10:50 AM is the end time.
DurationAnother term for elapsed time, referring to the length of time an event lasts.A concert has a duration of 3 hours.
Time IntervalA segment of time between two specific points.The time interval between 8:00 AM and 12:00 PM is 4 hours.
12-hour format (AM/PM)A time notation system where the day is divided into two 12-hour periods...
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Core Formulas
Calculating Elapsed Time
$\text{Elapsed Time} = \text{End Time} - \text{Start Time}$
Use this rule when you know when an event started and when it ended, and you want to find out how long it lasted.
Calculating End Time
$\text{End Time} = \text{Start Time} + \text{Duration}$
Use this rule when you know when an event began and how long it lasted, and you want to find out when it will finish.
Calculating Start Time
$\text{Start Time} = \text{End Time} - \text{Duration}$
Use this rule when you know when an event finished and how long it lasted, and you want to find out when it began.
Time Unit Conversions
$1 \text{ hour} = 60 \text{ minutes}$, $1 \text{ day} = 24 \text{ hours}$
Essential for performing calculations when time units are mixed or when borrowing/car...
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Challenging
A recipe states a roast must cook for 3.75 hours. If the roast is placed in the oven at 1:10 PM, at what time should it be taken out?
A.4:55 PM
B.4:45 PM
C.4:85 PM
D.5:05 PM
Challenging
A team meeting is scheduled to run from 1:00 PM to 2:30 PM. The main presentation is 55 minutes long. The team leader arrives at 12:50 PM and leaves at 2:45 PM. A 15-minute Q&A session is planned after the presentation. What is the total duration allocated for the meeting itself, ignoring when people arrived or left?
A.1 hour, 55 minutes
B.1 hour, 30 minutes
C.1 hour, 10 minutes
D.1 hour, 40 minutes
Challenging
A family begins a road trip at 7:00 AM. They drive for 2 hours and 40 minutes, take a 35-minute break, drive for another 3 hours and 10 minutes, stop for a 1-hour lunch, and then drive for 1 hour and 55 minutes to reach their destination. What time do they arrive?
A.3:20 PM
B.4:20 PM
C.3:40 PM
D.4:00 PM
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