Question

a man rode a bicycle a straight distance at a speed of 10 miles per hour. he came back the same way, travelling the same distance at a speed of 20 miles per hour. what was the man's total number of miles for the trip back and forth if his total travelling time was 1 hour?

Answer 1

Let d=the distance from point A to point B. In other words, it's the distance he travels in one direction.

Recall that time is equal to distance over velocity. So his time for the forward trip is
t=d/10

And the time for his second trip is
t=d/20

We know the sum of these times is 1 hour. So d/10 + d/20 = 1. Multiply both sides by 20:

2d+d=20
3d=20
d=20/3 miles

Since he goes forward and backward his total distance is 2d or
40/3 miles

Answer 2

it says here that ur answer is wrong :(

Answer 3

It says here that your spelling of "your" is wrong :-)

20 mph * 1/3 hour = 20/3 miles
10 mph * 2/3 hour = 20/3 miles
20/3 + 20/3 = 40/3 = 13.333 miles

The answer is correct.