Question

An emergency vehicle travels 10 miles at a speed of 50 miles per hour. How fast must the vehicle travel on the return trip if the round-trip travel time is to be 20 minutes?
1. 72 miles per hour
2. 75 miles per hour
3. 65 miles per hour
4. 78 miles per hour

Answer 1

Distance = 10 miles (Given)

Speed = 50 miles per hour (Given)

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STEP 1: Find time taken for to reach destination:

Time taken = Distance ÷ Speed

Time taken = 10 ÷ 50 = 1/5 hour

1/5 hour = 1/5 x 60 = 12 mins

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STEP 2: Find time remaining for the returned trip

Total time = 20 mins

Time for returned trip = 20 - 12 = 8 min

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STEP 3: Find speed needed for the returned trip:

8 mins = 8/60 = 2/15 hour

Speed = Distance ÷ Time

Speed = 10 ÷ 2/15

Speed = 10 x 15/2

Speed = 150/2

Speed = 75 miles per hour

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Answer: 75 miles per hour

Answer 2

Hey there!

Speed = Distance ÷ Time

Distance given = 10 miles

Speed given = 50 miles per hour

Time = ' x '

Find out time

50 = 10 ÷ x

50 x = 10

x = 1 ÷ 5 hours

x = 12 minutes

Total trip = 20 minutes

Remaining time = 8 minutes

NOW,

Time = 8 min ( 8 ÷ 60 ) hours = ( 2 ÷ 15 ) hours

Speed = ' x '

Distance = 10 miles ( as we will just have to ride back )

Speed = Distance ÷ Time

x = ( 10 ) ÷ ( 2 ÷ 15 )

x = ( 10 ) × ( 15 ÷ 2 )

x = 150 ÷ 2

x = 75

The speed will have to be 75 miles per hour

Hope my answer helps!

#PeaceOut

#FIERCE