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8th Class Mathematics Direct and Inverse Proportions Question Bank Direct and Inverse Proportions

  • question_answer
    A worker is paid Rs. 139.20 for 3 days.
    (i) What will he get in the month of June (in Rs,)?
    (ii) For how many days will he be working for Rs. 696?

    A)
    (i) (ii)
    1392 15
                   

    B)
    (i) (ii)
    15 1392
                   

    C)
    (i) (ii)
    1382 20

    D)
    (i) (ii)
    1392 20

    Correct Answer: A

    Solution :

              Let \[\text{Rs}\text{. }{{\text{x}}_{\text{2}}}\] be paid in the month of June.
    Amount paid (x) (in Rs.) \[{{\text{x}}_{1}}=139.20\] \[{{\text{x}}_{\text{2}}}\]
    No. of days (y) \[{{\text{y}}_{1}}=3\] \[{{y}_{2}}=30\]
    Since, it is a case of direct proportion. \[\therefore \frac{{{x}_{1}}}{{{y}_{1}}}=\frac{{{x}_{2}}}{{{y}_{2}}}\Rightarrow \frac{139.20}{3}=\frac{{{x}_{2}}}{30}\] \[\Rightarrow {{x}_{2}}=\frac{139.20\times 30}{3}\Rightarrow {{x}_{2}}=1392\]. Thus, Rs. 1392 will be paid in the month of June. (ii) Let \[{{y}_{2}}\] be the number of days he will work for Rs. 696.
    Amount paid (x) (in Rs.) \[{{x}_{1}}=139.20\] \[{{x}_{2}}=696\]
    No. of days (y) \[{{y}_{1}}=3\] \[{{y}_{2}}\]
    It is a case of direct proportion. \[\therefore \frac{139.20}{3}=\frac{696}{{{y}_{2}}}\Rightarrow {{y}_{2}}=\frac{696\times 3\times 10}{1392}\] \[\Rightarrow {{y}_{2}}=15\] Thus, he will work 15 days for Rs. 696.


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