Question

Concept of compound variation in unitary method for 3 quantity

Answer 1

24 painters working for 7 hours paint a house in 16 days.

1 painter working for 7 hours paints a house in 16 × 24 days.

1 painter working for 1 hour paints a house in 16 × 24 × 7 days.

Let the required number of painters be x, then;

x painters working for 1 hour a day paint the house in (16 × 24 × 7)/x days

x painters working for 8 hours a day paint the house in (16 × 24 × 7)/(x × 8) days

But the number of days given = 12

According to the problem;

(16 × 24 × 7)/(x × 8) = 12

2688/8x = 12

8x × 12 = 2688

96x = 2688

x = 2688/96

x = 28

Therefore, 28 painters working for 8 hours a day will finish the same work in 12 days.