8th Class Mathematics Related to Competitive Exam Question Bank Arithmetic

  • question_answer
    DIRECTIONS: Reade the following passage and answer the questions that follow. PASSAGE - 1 If \[=P{{\left( 1+\frac{R}{100} \right)}^{n}}\] is the value of an article at certain time which increases at the rate of \[=\frac{R}{{{\left( 1+\frac{R}{100} \right)}^{n}}}\]for first \[{{R}_{1}}%\]years and decreases at the rate of \[{{R}_{2}}%\] for next \[=P\left( 1+\frac{{{R}_{1}}}{100} \right)\times \left( 1+\frac{{{R}_{2}}}{100} \right).\] years, then the value of the article V at the end of \[=P{{\left( 1-\frac{R}{100} \right)}^{n}}.\] years is given by       \[=\frac{P}{{{\left( 1-\frac{R}{100} \right)}^{n}}}\] Population of Chhapra district was 200000 on the last day of the year 2005. During next year is increased by 5% but due to an epidemic it decreased by 2% in the following year, then the population at the end of the year 2007 is

    A) 205000                 

    B) 205800                

    C) 206000                 

    D) 205700       

    Correct Answer: B

    Solution :

    Population of Chhapra district \[CI=A-P=8405-8000=Rs.405.\] \[=25000\times \left( 1+\frac{4}{100} \right)\times \left( 1+\frac{5}{100} \right)\times \left( 1+\frac{8}{100} \right)\]        


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