Quantitative Aptitude Ques 121
Question: Three numbers A, B and C are in the ratio 1: 2: 3. Their average is 600. If A is increased by 10% and B is decreased by 20%, then to get the average increased by 5%. C will be increased by [NICL (AO) 2014]
Options:
A) 90%
B) 10%
C) 15%
D) 18%
E) 20%
Show Answer
Answer:
Correct Answer: E
Solution:
- Let A = x, B = 2x and C = 3x
Then, $ \frac{x+2x+3x}{3}=600 $
$ \Rightarrow $ $ \frac{6x}{3}=600 $ $ \frac{x}{3}=100 $
$ \Rightarrow $ $ x=300 $
$ \therefore $ Numbers are 300, 600 and 900. New average = 105% of $ 600=\frac{600\times 105}{100}=630 $ Now, let
$ \Rightarrow $ $ 300\times \frac{110}{100}+600\times \frac{80}{100}+y=1890 $
$ \Rightarrow $ $ 330+480+y=1890 $
$ \Rightarrow $ $ 810+y=1890 $
$ \Rightarrow $ $ y=1890-810=1080 $
$ \therefore $ Increase in $ C=1080-900=180 $ % increase in $ C=\frac{180}{900}\times 100=20% $
BETA
