9. A manufacturer sells a scooter at 10% profit to wholesaler who in turn sells it to a retailer at 20% profit. If the price paid by the retailer is Rs. 13200, how much the scooter costs to the manufacturer?
a. 8500
b. 10000
c. 11000
d. 12000

Answer: B

Explanation:
Let the manufacturer bought the scooter for $x$ rupees.
Given, $x \times 110\% \times 120\% = 13200$
$ \Rightarrow x = \dfrac{{13200}}{{110\% \times 120\% }}$ = $\dfrac{{13200}}{{\dfrac{{11}}{{10}} \times \dfrac{{12}}{{10}}}}$ = $\dfrac{{13200 \times 10 \times 10}}{{11 \times 12}}$ = 10000

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10. A man bought some oranges at the rate of 3 oranges for one rupee and equal number of oranges at the rate of 2 oranges for one rupee. What is his profit, if he sells 2 oranges for one rupee.
a. 1000
b. 1200
c. 1300
d. 1400

Answer: C

Explanation:
Let us take LCM of quantities purchased and sold i.e. LCM of 3, 2 and 2 is 6.
Now, cost price of 6 oranges @ 3 oranges for a rupee = $\displaystyle\frac{{\rm{1}}}{{\rm{3}}}$ × 6 = Rs. 2
And, cost price of 6 oranges @ 2 oranges for a rupee = $\displaystyle\frac{{\rm{1}}}{{\rm{2}}}$ × 6 = Rs. 3
Therefore, Cost price of 12 (i.e. 6 + 6) oranges = Rs. 2 + Rs. 3 = Rs. 5
Selling price of 12 oranges = $\displaystyle\frac{{\rm{1}}}{{\rm{2}}}$ × 12 = Rs. 6
Profit = Rs. 6 - Rs. 5 = Re. 1 on Rs. 5
Therefore, Profit percent = $\displaystyle\frac{{\rm{1}}}{{\rm{5}}}$ = 20%

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11. If the cost price of 11 oranges is equal to selling price of 10 oranges. Find profit per cent.
a. $37\displaystyle\frac{1}{2}$ %
b. 60%
c. 75%
d. None of these

14. Goods are purchased for Rs. 450 and one-third is sold at a loss of 10%. At what profit per cent should the remainder be sold so as to gain 20% on the whole transaction?
a. 35%
b. 42%
c. 45%
d. 48%

Answer: A

Explanation:
Assume Total cost price of goods = Rs. 450
Our target SP of total goods = $\dfrac{{120}}{{100}} \times 450 = Rs.540$
One-third of the goods costs = 450/3 = Rs.150
SP of one-third goods = $\dfrac{{90}}{{100}} \times 150 = Rs.135$
SP of the remaining goods = 540 – 135 = Rs. 405
CP of remaining (two-thirds) goods = Rs. 300
Hence, profit per cent = $\dfrac{{105}}{{300}} \times 100 = 35\% $

Alternate method:
Applying weighted average, one part of quantity sold at a loss of 10% (or a profit of –10%) and balance two units are to be sold at x% to give a overal profit of 20%.
Hence, overall profit is given by , $\dfrac{{mx + ny}}{{m + n}}$ = $\dfrac{{1 \times ( - 10\% ) + 2 \times (x\% )}}{{1 + 2}} = 20\% $

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15. A retailer buys goods at 10% discount on its marked price and sells them at 20% higher than the marked price. What is his profit per cent?
a. 30%
b. 33.33%
c. 37.5%
d. 40%

Answer: B

Explanation:
Let, marked price of the article = Rs. 100, Then, its cost price = Rs. 100 - Rs. 10 = Rs. 90, And selling price = Rs. 100 + Rs. 20 = Rs. 120
Therefore, Profit = Rs. 30 on Rs. 90 i.e. $\displaystyle\frac{{\rm{1}}}{{\rm{3}}}$ = 33.33%

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16. A dishonest merchant professes to sell his goods at cost price, but uses a weight of 900 grams for one kg. weight. What is his profit per cent?
a. 9.8
b. 10
c. 10.5
d. 11 1/9%

Answer: D

Explanation:
Assume 1gm costs 1 rupee. The merchant gives 900 grams charging the price of 1000 grams.
His gain is 100 grams on every 900 grams. i.e., for Rs.900 investment his gain is Rs.100.
Therefore, Profit percent = $\displaystyle\frac{{{\rm{100}}}}{{{\rm{900}}}}{\rm{ \times 100 = 11}}\displaystyle\frac{{\rm{1}}}{{\rm{9}}}$%