Discount Ques 15
Question
A single discount equivalent to the discount series 20%, 10% and 15% is
(1) 36.1%
(2) 38.8%
(3) 31.6%
(4) 38.2%
(5) None of these
(SBI PO Phase-I (Preliminary) Online Exam. 20.06.2015)
Show Answer
Answer: (2)
Solution: (2)
Let the marked price be x. Then, amount after discount series
$ =[ ( x-\frac{20}{100}x )-\frac{10}{100}\times ( x-\frac{20x}{100} ) ] $
$ -\frac{15}{100}[ ( x-\frac{20x}{100} )-\frac{1}{10}( x-\frac{20x}{100} ) ] $
$ =[ ( x-\frac{x}{5} )-\frac{1}{10}( x-\frac{x}{5} ) ]-\frac{15}{100}[ \frac{4x}{5}-\frac{1}{10}( \frac{4x}{5} ) ] $
$ =[ \frac{4x}{5}-\frac{1}{10}( \frac{4x}{5} ) ]-\frac{15}{100}[ \frac{40x-4x}{50} ] $
$ =\frac{(40-4)x}{50}-\frac{15}{100}( \frac{36x}{50} ) $
$ =\frac{36x}{50}-\frac{15\times 36x}{100\times 50}=\frac{612x}{1000} $
Discount $ =x-\frac{612}{1000}=\frac{388}{1000}\times 100=38.8 $ %
BETA
