Question

It takes Kristin ten hours to paint a fence DeShawn can paint the same fence in eight hours. If they worked together how long would it take them?

Answer 1

Since it takes Kristin 10 hours to paint a fence

Hence the rate at which the job will be done per hour is is

`(1)/(10)=0.1`

Since it takes Deshawn 8 hours to paint a fence

Hence the rate at which the job will be done per hour is

`(1)/(8)=0.125`

Since Kristin do the job at a rate of 0.1 per hour and Deshawn does the job at a rate of 0.125 per hour then with the combined efforts the rate at which the job will be done is

`0.1+0.125=0.225`

Hence the job will be don at a rate of 0.225 per hour

The time it will take to complete the job will be

`(1)/(0.225)=4.44`

Therefore it will them approximately 4 hours to complete the job if they work together