Question

A can do a piece of work in 5 days and B can do the same work in (x + 5) days. The total number of days taken by A and B, working together, is `3 1/3`. The value of x is ______.

विकल्प

• 5

• 10

• 15

• `2 1/2`

Answer 1

A can do a piece of work in 5 days and B can do the same work in (x + 5) days. The total number of days taken by A and B, working together, is `3 1/3`. The value of x is 5.

Explanation:

Given A's alone one day work = `1/5`

And B's alone one day work = `1/(x + 5)`

∴ (A + B)'s together one day work = `1/5 + 1/(x + 5)`

No. of days taken by A and B working together = `3 1/3 = 10/3`

∴ (A + B)'s together one day work = `3/10`

Thus, `1/5 + 1/(x + 5) = 3/10`

`\implies 1/(x + 5) = 3/10 - 1/5`

= `(3 - 2)/10`

= `1/10` 

`\implies` x + 5 = 10

`\implies` x = 10 – 5 = 5