Question

It takes 63 minutes for 4 people to paint 9 walls.

How many minutes does it take 7 people to paint 4 walls?

Answer 1

63 / 9 = 7
7 / 4 = 1.75
It takes 1.75 minutes for 1 person to paint 1 wall...
1.75 * 4 = 7
7 * 7 = 49
It took 49 minutes for 7 people to paint 4 walls...

Answer 2

7 people will take 16 minutes to paint 4 walls.

Explanation:

Since, if
`x_1` people take
`n_1` times for
`w_1` work and in the same kind of work
`x_2` people take
`n_2` time for
`w_2` work,

Then,

`(x_1* n_1)/(w_1)=(x_2* n_2)/(w_2)`

Here,
`x_1=4`,
`n_1=63`,
`w_1=9`,

`x_2=7`,
`w_2=4`

By substituting the values in the above formula,

`(4* 63)/(9)=(7n_2)/(4)`

By the cross multiplication,

`1008=63n_2`

`\implies n_2=(1008)/(63)=16`

Hence, 7 people will take 16 minutes to paint 4 walls.