My friend sets out walking at a speed of $3$ miles per hour. i set out behind her $5$ minutes later at $4$ miles per hour. for how many minutes will my friend have been walking when i catch up to her?

Solution:

we are given that

My friend sets out walking at a speed of 3 miles per hour.

I set out behind her 5 minutes later at 4 miles per hour.

we have been asked to find

For how many minutes will my friend have been walking when I catch up to her?

Let the required time be t then we can write

As we know that

When they meet up then difference of distance traveled becomes zero.

so we can write

Hence the required time is 20 minutes.

step-by-step explanation:

the multiplicative inverse of a fraction a/b is b/a. for the multiplicative inverse of a real number, divide 1 by the number. for example, the reciprocal of 5 is one fifth 1/5 or 0.2, and the reciprocal of 0.25 is 1 divided by 0.25, or 4.