Question:
Tick (✓) the correct answer
3 persons can build a wall in 4 days, then 4 persons can build it in
(a) $5 \frac{1}{3}$ days
(b) 3 days
(c) $4 \frac{1}{3}$ days
(d) none of these
Solution:
(b) 3 days
Let x be number of days taken by 4 persons to build the wall.
More number of persons will take less time to build the wall.
So, it is a case of inverse proportion.
Now, $3 \times 4=4 \times x$
$\Rightarrow x=3$
Therefore, 4 persons can build the wall in 3 days.