Question

A contractor estimates that $3$ persons could rewire Jasminders house in $4$ days. If he uses $4$ persons instead of three, how long should they take to complete the job?

Answer 1

According to question,

$\begin{array}{rcl}3\mathrm{persons}\mathrm{can}\mathrm{complete}\mathrm{the}\mathrm{work}\mathrm{in}& =& 4\mathrm{days}\\ 1\mathrm{person}\mathrm{can}\mathrm{complete}\mathrm{the}\mathrm{work}\mathrm{in}& =& 4\times 3\mathrm{days}\\ \therefore 4\mathrm{persons}\mathrm{can}\mathrm{complete}\mathrm{the}\mathrm{work}\mathrm{in}& =& \frac{4}{4}\times 3=3\mathrm{days}\end{array}$

Hence, the number of days taken by $4$ persons will be $3days$.