If 8 men can reap 80 hectares in 24 days, then how for ` 21.25, then the number of lamps, which can be many hectares can 36 men reap in 30 days? lighted 4 hours daily for 30 days, for ` 76.50, is
(a)100
(b)400 120
(c)150
(d)160
Answer
Answer (as printed): D
Explanation
Let the required number of hectares be x. Then, More men, More hectares (Direct Proportion) More days, More hectares (Direct Proportion) Men 8 : 36 : : 80 : x Days 24 : 30 ∴ 8 × 24 × x = 36 × 30 × 80 (36 × 30 × 80) ⇔x= ⇔ x = 450. (8 × 24)
Explanation as extracted from the printed page; notation may be imperfect.