7th Class Mathematics Comparing Quantities Question Bank Comparing Quantities

  • question_answer Divide Rs. 100000 into two parts so that the S.I on the first part for 6 years at 10% per annum is equal to S.I on the second part for 3 years at 20% per annum.

    A)  Rs. 40000, Rs. 60000

    B)  Rs. 30000, Rs. 70000

    C)  Rs. 60000, Rs. 40000

    D)  Rs. 50000, Rs. 50000

    Correct Answer: D

    Solution :

    (d) Let one part by Rs.\[x\]. Then the other part is\[Rs.\,\,(100000-x)\]. \[{{T}_{1}}=6\] years; \[{{R}_{1}}=10%\] \[\therefore \]  S.I. (on first part) \[\frac{x\times 6\times 10}{100}=Rs.\frac{3x}{5}\] \[{{T}_{2}}=3\] years; \[{{T}_{2}}=3\] S.I (on second part) \[\frac{\left( 100000-x \right)\times 3\times 20}{100}\] \[=\left( 100000-x \right)\times \frac{3}{5}\] \[\Rightarrow \]\[\frac{3x}{5}=\left( 100000-x \right)\times {}^{3}/{}_{5}\Rightarrow x=100000-x\] \[\Rightarrow \]\[x=50000\]


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