Question

One person can do a certain job in 10 minutes and another person to the same job and 15 minutes how many minutes will it take to do the job together

Answer 1

6 minutes

Explanation:

Person A does 1 job in 10 minutes.

In 1 minute, person A does 1/10 of the job.

Person B does the same job in 15 minutes.

In 1 minute, person B does 1/15 of the job.

Working together, in 1 minute the do

1/10 + 1/15 of the job.

Working together, they take t minutes to do the job.

In 1 minute, they do 1/t of the job.

1/10 + 1/15 = 1/t

3/30 + 2/30 = 1/t

5/30 = 1/t

1/6 = 1/t

t = 6

Answer 2

6 minutes

Explanation:

The equation for time together is

1/a+1/b = 1/c where a and b are the times alone and c is the time together

1/10 + 1/15 = 1/c

Multiply by the least common denominator to clear the fraction

30c(1/10 + 1/15 = 1/c)

3c+ 2c = 30

5c = 30

Divide by 5

5c/5 = 30/5

c = 6