12 girls can do a a piece of work in 30 days, working 8 hours a day . In how many days 18 girls can do the same piece of work while working 4 hours a day?
Answer & explanation
Correct answer: option 3
M1 × D1 × T1 = M2 × D2 × T2
12 × 30 × 8 = 18 × D2 × 4
D2 = 12 × 30 × 8/ 18 × 4
D2 = 40 days