Ok, so the answer i find logical is $21$%. Like :
100 bucks paid, 110 items got. (10% profit).
Then, 110 items you sell at 10% profit, you get 121 items worth of bucks. So, 100 bucks investment, 121 bucks return. Profit 21%.
More Formally :
$10$% fraud on purchase : Buying 110 items for price of 100. Cost Price/item = $\frac{10}{11}$
$10$% fraud on sale : Getting 110 bucks by selling 100 items. Thus, Selling Price/item = $\frac{11}{10}$
Thus, overall Profit Percentage :$$\frac{\frac{11}{10} – \frac{10}{11}}{\frac{10}{11}} * 100 = 21$$
The book says Profit Percentage is $22\frac{2}{9}$%
What am i doing wrong ?
Best Answer
Ok, So i guess this is how it goes :
Lets say 1 item cost 1 buck.
Thus, buy 100 items for 90 bucks (10% purchase fraud).
Now, sell 100 items for 110 bucks (10% sale fraud).
Total money in : 90 bucks.
Total money out : 110 bucks.
Profit Percentage = $\frac{110 - 90}{90}*100$ = $22\frac{2}{9}$