Answer:
50 years
Step-by-step explanation:
Since time T to complete work W is inversely proportional to manpower M,
We get the proportional relationship
T ∝ 1/M
which can be written as an equation in the form:
T = k/M where k is the constant of proportionality
Cross multiplying, we get k = T· M
Given T = 20 when M = 20,000 we get k = 20 x 20,000
For M' = 8000(people) T' = k/M'
= 20 x 20,000/8000= 20 x 20/8 (divide numr and denr by 1000)
=400/8
= 50 years
