A can do a work in 15 days and B in 20 days. If they work on it together for 4 days, then the fraction of the… · ABC26GN3468
Subject: General Aptitude · Chapter: Time and Work
A can do a work in 15 days and B in 20 days. If they work on it together for 4 days, then the fraction of the work that is left is :
(a)$\frac{1}{4}$
(b)$\frac{1}{10}$
(c)$\frac{7}{15}$
(d)$\frac{8}{15}$
Answer
Explanation
A's 1 day's work $=\frac{1}{15}$; B's 1 day's work $=\frac{1}{20}$. (A+B)'s 1 day's work $=\left(\frac{1}{15}+\frac{1}{20}\right)=\frac{7}{60}$. (A+B)'s 4 days' work $=\left(\frac{7}{60} \times 4\right)=\frac{7}{15}$. $\therefore$ Remaining work $=\left(1-\frac{7}{15}\right)=\frac{8}{15}$.
Explanation as extracted from the printed page; notation may be imperfect.
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