A certain car travels a mile at 60 mph. It spends one second less to t

Question

A certain car travels a mile at 60 mph. It spends one second less to travel the next mile. What is its average speed for the second mile?

A. 59 mph
B. 61 mph
C. 3600/59 mph
D. 62 mph
E. 63 mph

chetan2u · Answer

60mph means 60 miles in 60minutes or 60miles in 3600 seconds or 1 mile in 60 seconds..
Now it takes 59 seconds to travel 1 mile, so speed will be 1 mile in 59seconds or 1*3600 mile in 59 hr...so  \frac{3600}{59} mph

Kinshook · Answer

Time taken to travel a mile = 1 min = 60 s
One second less ; Time taken to travel next mile = 59 s

Average speed = 60 mph *60/59 = 1600/59 mph

IMO C

ccooley · Answer

Take it step by step. We don't know the amount of time it takes to travel the first mile, and we'll need to know that in order to subtract one second from it. So, start there.

Distance = Rate * Time
1 mile = 60 mph * Time
Time = 1 mile / 60 mph = 1/60 hours

We need this time in seconds, though, not hours. Here's the safest way to convert, if you don't immediately recognize this value as being equal to 1 minute or 60 seconds.

\frac{1}{60}  hours *  \frac{60 minutes}{1 hour}  *  \frac{60 seconds}{1 minute}

\frac{1}{60}  *  \frac{60}{1}  *  \frac{60 seconds}{1}

60 seconds

So, the first mile took 60 seconds, and the second mile took 1 second less, or 59 seconds.

The question asks for the rate in miles per hour, so this has to get converted back to hours. Do the same thing, except backwards:

59 seconds *  \frac{1 minute}{60 seconds}  *  \frac{1 hour}{60 minutes}

59 *  \frac{1}{60}  *  \frac{1}{60}  hours

59/3600 hours

Finally, use another distance/rate/time equation to find the rate:

1 mile = Rate * 59/3600 hours

Rate = 1/(59/3600) miles/hours = 3600/59 miles per hour

However, this would also be a great problem to guess on. The difference in time is only a single second. Because you're going faster, the speed should increase, not decrease. However, it should only increase by a small amount - a larger change would probably cause a bigger change in the time to travel one mile. Guess either (B) or (C).

Ilishar · Answer

First Mile: v = 60mph; distance = 1 mile => time = 60 seconds

Second Mile: V = ?; distance = 1 mile => time = 59 seconds
v = distance/time = 1mile/59 seconds (* 59 seconds = 59/60*60 hrs)
v = 1 mile(60*60)/59 mph = 3600/59 mph => Option C correct

Archit3110 · Answer

time per mile ; 1/60 hrs or say ; 3600/60 ; 60 seconds
next mile is covered in 1 second less ; 59 seconds
so the avg speed for next mile ; 59/3600 hrs or say 1/59 *3600 = 3600/59 mph
IMO C

ScottTargetTestPrep · Answer

At a rate of 60 mph, it takes 1/60 hour = 1/60 x 3600 = 60 seconds to travel 1 mile. So the next mile takes 59 seconds, and the rate is 1/59 mile per second, or 1/59 x 3600 = 3600/59 mph.

Answer: C

A certain car travels a mile at 60 mph. It spends one second less to t

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A certain car travels a mile at 60 mph. It spends one second less to t

Prep Toolkit

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