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8th Class Mathematics Related to Competitive Exam Question Bank Arithmetic

  • question_answer
    Six diesel engines consume 900 liters of diesel, when each one is running for 5 hrs a day. How much diesel will be required by 9 engines, each running 8 hrs a day when 5 diesel engines of former type consume as much diesel as 8

    A) 1500 lit                 

    B) 1250 lit

    C) 1350 lit                 

    D) None of these

    Correct Answer: C

    Solution :

    Let m and n be the number of engine of former type and later type respectively So,  \[\frac{m}{n}=\frac{5}{8}=\frac{8m}{5}\] So,  \[n=\frac{8\times 6}{5}=\frac{48}{5}=\frac{48}{5}\]
    No. of engines Diesel working hrs (in litres)
    \[{{R}_{2}}=24%\] 900 5
    9 x 8
    Since, number of engines is in direct variation with diesel and working hours. So,  \[\left. \begin{align}   & \frac{48}{5}:9 \\  & 5:8 \\ \end{align} \right\}::900:x\]       \[\frac{100+{{T}_{1}}{{R}_{1}}}{100+{{T}_{2}}{{R}_{2}}}=\frac{100+3\times 12}{100+10\times 24}=\frac{136}{340}=\frac{2}{5}\]


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