8th Class Mathematics Comparing Quantities Question Bank Comparing Queantities

  • question_answer Two numbers A and B are such that the sum of 5% of A and 4% of B is two- third of the sum of 6% of A and 8% of B. Find the ratio of A : B

    A)  2 : 3                            

    B)  1 : 1          

    C)  3 : 4                            

    D)  4 : 3

    Correct Answer: D

    Solution :

    (d):5% of A+4% of B \[=\frac{5A}{100}+\frac{8B}{100}\] 6 % of A+8% of B \[=\frac{6A}{100}+\frac{8B}{100}\] Now \[\frac{5A+4B}{\cancel{100}}=\frac{2}{3}\left( \frac{6A+8B}{\cancel{100}} \right)\] \[\Rightarrow 3\left( 5A+4B \right)=2\left( 6A+8B \right)\] \[\Rightarrow 15A+12B=12A+16B\] \[\Rightarrow 3A=4B\Rightarrow \frac{A}{B}=4/3\].

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