Question

10 machines can wash 20 cars in 6 hours. In how many hours can 15 machines wash 40 cars?

• A. 8
• B. 7
• C. 15
• D. 12
• E. 6

Answer 1

The correct option is A 8

Washing cars is a work, so
$M_1\times H_1\times W_2=M_2\times H_2\times W_{1}10\times 6\times 40=15\times H_2\times 20$
Solve, $H_2=8hrs$