Question

40 people take 10 days to dig a well. Using the theory of variation , how many extra people will be required to dig the well in 8 days.

• A. 8
• B. 9
• C. 10
• D. 12

Answer 1

The correct option is C

10

Let the number of people be P and Days be D.

Since increasing the people decreases the number of days,

P ∝ 1/D

$\Rightarrow$ P = k/D

Putting the values of P and D in this equation we get - k = D*P = 40 * 10 = 400

Now, putting the value of k and new D we get - P = 400/8 = 50

$\therefore$ The number of extra people required = 50 - 40 = 10