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Railways R.R.C. (Patna) Solved Paper Held on 1st Shift 2-11-2014

  • question_answer
    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 decreased by 20%, then to get the average increased by 5%, C should be increased by?

    A) 90                                

    B) 100

    C) 180                              

    D) 150

    Correct Answer: D

    Solution :

    Suppose three numbers are x, 2x and 3x. Then,    \[x+2x+3x=3\times 600\] \[6x=3\times 600\] \[x=300\] Now,     \[A=\frac{300\times 110}{100}=330\] \[B=\frac{2\times 300\times 80}{100}=480\] \[Average=\frac{600\times 105}{100}=630\] Hence, C should be increased by \[=3\times 630-(330+480)-3\times 300\] \[=3\times 630-810-900\] \[=1860-1710\] \[=150\]


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