Quantitative Aptitude Ques 1704
Question: A can do a piece of work in 15 days. With the help of A, B can do it in $ 6\frac{2}{3} $ days. B can do it alone in
Options:
A) 13 days
B) 8 days
C) 10 days
D) 12 days
Show Answer
Answer:
Correct Answer: D
Solution:
- Total work done by A in 15 days.
$ \therefore $ A’s one day work $ =\frac{1}{15} $ A and B can do working together in $ 6\frac{2}{3} $ days $ =\frac{20}{3} $ days.
$ \therefore $ One day work of A and $ B=\frac{3}{20}. $ Let work done B alone be x days.
$ \therefore $ One day work of $ B=1/x $
$ \therefore $ $ \frac{1}{x}+\frac{1}{15}=\frac{3}{20} $
$ \Rightarrow $ $ \frac{1}{x}=\frac{3}{20}-\frac{1}{15} $
$ \Rightarrow $ $ \frac{1}{x}=\frac{9-4}{60} $
$ \Rightarrow $ $ \frac{1}{x}=\frac{5}{60} $
$ \Rightarrow $ $ \frac{1}{x}=\frac{1}{12} $
$ \therefore $ One day work of $ B=1/12 $ Hence, B alone can do complete work in 12 days.
BETA
