SOLUTION: a car travels 40 mph for 20 miles, 36 mph for 24 miles, and 48 mph for 16 miles. what is its average speed? ( show work)

Question 178882: a car travels 40 mph for 20 miles, 36 mph for 24 miles, and 48 mph for 16 miles. what is its average speed? ( show work)
Found 2 solutions by Alan3354, nerdybill:
Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
a car travels 40 mph for 20 miles, 36 mph for 24 miles, and 48 mph for 16 miles. what is its average speed?
---------------
Find the total distance:
20 + 24 + 16 = 60 miles.
Find the total time:
20 miles/40 mph = 0.5 hrs = 30 minutes
24 miles/36 mph = 2/3 hrs = 40 minutes
16 miles/48 mph = 1/3 hrs = 20 minutes
Time = 90 mins = 1.5 hours
Avg speed = 60 miles/1.5 hours
= 40 mph
Answer by nerdybill(7384) (Show Source): You can put this solution on YOUR website!
a car travels 40 mph for 20 miles, 36 mph for 24 miles, and 48 mph for 16 miles. what is its average speed? ( show work)
.
Total miles driven: 20+24+16 = 60 miles
.
To calculate the "time" driven, you must use the distance formula for each leg.
d = rt
solving for t:
t = d/r
where
t is time
d is distance
r is rate
.
1st leg:
t = d/r = 20/40 = 1/2 hours
2nd leg:
t = d/r = 24/36 = 2/3 hour
3rd leg:
t = d/r = 16/48 = 1/3 hour
.
total time = 1.5 hours
.
Avg speed = "total distance"/"total time"
Avg speed = 60/1.5 = 40 mph

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