Question

15 men can build a wall in 42 hours, how many men will be required for the same work in 30 hours

Answer 1

Answer:

This question can be solved using direct and inverse variation. Direct variation can be solved using unitary method that is common sense like if you buy 10 chocolates for 100 rupees how many rupees would you pay for 20 - this is simple as if 10 chocolates is 100 then 20 would be 200. HOWEVER,  Inverse Variation is when one value increase the other value decreases and they are proportional. They have a formula called x1/x2 = y2/y1.

In this problem we can use this formula, x1/x2 = 15/42 and y2/y1 = 30/x

so hence 15/42 = 30/x

= 15x = 30*42

x= 1260/15

 = 84

Therefore 84 is the answer.