Engineering Maths - Percentage

11. One merchant correctly calculates his percentage profit on the cost price; another wrongly calculates it on the selling price. The difference in actual profits if both claim to make 17 .5 % profit on goods sold at Rs.3760 is

  • Option : A
  • Explanation :

    CP of the merchant who calculates his % profit on CP = (3760/1.175) =Rs.3200
    His profit = 0.175 x 3760 = Rs.560
    Profit of the merchant who calculates his % profit on SP = 0.175 x 3760 = Rs.658
    Difference in profit = 658 - 560 =Rs.98.

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13. A sports goods shop owner has 6 packets of balls each containing the same number of balls. If he sells each ball at Rs. 8 he gains Rs.96. If there were 1 ball less in each packet and he sells each ball at Rs.9 then he gains Rs.90 in the transaction. The cost price of each packet of balls is

  • Option : B
  • Explanation :

    Let there be n number of balls in each packet.
    ∴ 6n x 8 = CP + 96
    ⇒48n = CP + 96  ------------ (i)
    Also, 6 (n - 1) x 9 = CP + 90
    ⇒54n - 54 = CP + 90
    54n = CP + 144 ------------(ii)
    Solving equations (i) and (ii),
    we get, n = 8
    ∴ CP = 48 x 8 96 = 384 - 96 =  Rs.288
    Each packet cost = Rs.48.

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14. A man travels from A to B to buy goods which he can get 10% cheaper in B than in A. If expenses of the journey are 15 and he makes a clear saving of 10, how much does he pay for the goods?

  • Option : A
  • Explanation :

    Let CP in A be Rs. x
    ∴ CP in B = Rs. 0.9x
    ∴ 0.9x + 15 + 10 = x
    ⇒0.1x = 25
    ⇒x = 250
    ∴Price in B = 250 x 0.9 = Rs.225

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15. Three friends started a business of renting out air conditioners by investing Rs.20000, Rs. 24000 and Rs.216000, respectively. C gets 20% of total profit for repair and maintenance of the air conditioner. If in a particular year, C gets Rs. 487.50 less than total earnings of the other two, then total profit for the year is

  • Option : A
  • Explanation :

    80% of the total proit is divided in the ratio
    20000: 24000: 16000 = 5 : 6 : 4
    80% of total profit = 5x + 6x + 4x = 15x
    Total profit =(15x/80%)= 18.75x
    Share of C in profit = 4x + 20% of 18.75
    = 4x + 3.75x = 7.75x
    ∴Share of A in proit = 5x
    Share of B in proit = 6x
    ∴(6z + 5x) - 7.75x = 487.50
    ⇒3.25x = 487.50
    ⇒x = 150
    ∴Total profit = 18.75 x 150 = Z 2812.50.

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