Mathematics for IGCSE & O level - Proportion (Section 1 - No. 23)
The time it takes to complete a job is inversely proportional to the number of people working. If 3 people take 12 hours to complete a job, how long would it take 4 people?
6 hours
9 hours
16 hours
18 hours
説明
Time = k/people; 12=k/3, k=36. Therefore time=36/people; when people = 4, time = 36/4 = 9 hours.