Question 1190053: Sarah wants to arrive at her friend's wedding at 3:00 PM. The distance from Sarah's house to the wedding is 90 miles. Based on usual traffic patterns, Sarah predicts she can drive the first 20 miles at 60 miles per hour, the next 5 miles at 30 miles per hour, and the remainder of the drive at 65 miles per hour.
(a)How many minutes will it take Sarah to drive the first 20 miles?
(b)How many minutes will it take Sarah to drive the next 5 miles?
(c)How many hours will it take Sarah to drive the rest of the trip?
(d)What time should Sarah leave her house? (Give your answer using standard hour:minute clock format.)
Answer by math_tutor2020(3816)   (Show Source):
You can put this solution on YOUR website!
Part (a)
distance = rate*time
time = distance/rate
time = (20 miles)/(60 mph)
time = 1/3 hour
time = 20 minutes
note: to convert from hours to minutes, multiply by 60
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Part (b)
time = distance/rate
time = (5 miles)/(30 mph)
time = 1/6 hour
time = 10 minutes
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Part (c)
time = distance/rate
time = (90-20-5 miles)/(65 mph)
time = (65 miles)/(65 mph)
time = 1 hour
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Part (d)
Add up the durations from each previous part above
20 min + 10 min + 1 hour = 1 hour, 30 min
If she wants to arrive at 3:00 PM, then she needs to leave her house at 1:30 PM.
This is assuming that everything goes according to plan. Realistically, Sarah should have a bit of a buffer of say an extra 10 or 20 minutes (to account for possible bad traffic, construction, bad weather, etc).
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