Question

4 builders are building some new classrooms at Trinity. It takes them 5 months to build the classrooms. How long will it take 10 builders?

Answer 1

`\boxed{2months}`

Explanation:

B1 = 4

M1 = 5

B2 = 10

M2 = x (we have to find this)

Since it is an inverse proportion (more builders will take less time and vive versa), we'll write it in the order of

=> B1 : B2 = M2 : M1

=> 4:10 = x : 5

Product of Means = Product of Extremes

=> 10*x = 4*5

=> 10x = 20

Dividing both sides by 10

=> x = 2 months

So, it will take 2 months to build classrooms by 10 builders.

Answer 2

it takes

`\boxed {\red {2 \: \: months}}`

for 10 builders

Explanation:

`4 \: \: \: builders = 5 \: month \\ 10 \: builders = x`

Let us solve

`4 = 5 \\ 10 = x`

so

`4 = x \\ 10 = 5`

use cross multiplication

`5 * 4 = 10 * x \\ 20 = 10x \\ (20)/(10) = (10x)/(10) \\ \green {x = 2}`