Question

Suhan can do a work in 15 days and Ankush in 20 days. If they work on it together for 4 days, then the fraction of the work that left is ______ (2 marks)

Answer 1

Suhan's one day work = $\frac{1}{15}$
Ankush one day work = $\frac{1}{20}$
(Suhan + Ankush) one day work = $\frac{1}{15}$ + $\frac{1}{20}$ = $\frac{7}{60}$
(1 mark)
(Suhan + Ankush) 4 day work = $\frac{7}{60}\times 4$ = $\frac{7}{15}$
Therefore, Remaining work = 1 - $\frac{7}{15}$ = $\frac{8}{15}$
(1 mark)