8th Class Mathematics Related to Competitive Exam Question Bank Arithmetic

  • question_answer
    If a certain sum is doubled in 8 years on simple interest, in how many years will it be 4 times?        

    A) 24                  

    B) 16

    C) 32                         

    D) 12

    Correct Answer: A

    Solution :

    Let sum be Rs. x so amount Rs.2x. So S.I. = Rs. x, \[C.I.=P\left[ \left( 1+\frac{{{R}_{1}}}{100} \right)\left( 1+\frac{{{R}_{2}}}{100} \right)....\left( 1+\frac{{{R}_{n}}}{100} \right)-1 \right]\] \[5\frac{1}{4}\] Now, for amount = Rs. 4 x \[A=P{{\left( 1+\frac{R}{100} \right)}^{5}}\left( 1+\frac{\frac{R}{4}}{100} \right)\] \[{{V}_{0}}\]      


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