A person bought 150 packets of choclate. He was able to sell 1/3...

Hi iNumbv,

The math involved in this question can be done in a variety of ways; it's just a matter of what method you find most comfortable.

Here, we're told that a person bought 150 packets of chocolate...

We can say that 1 packet cost $X

We then sell 50 each at....
a 5% profit = 1.05X each
a 0% profit = 1X each
a 10% loss = .9X each

Since the question focuses on the net profit or loss, we can ignore the 50 packets we sold for a 0% profit and focus on the other 100.

50(1.05X + .9X) =
50(1.95X)

IF we had 50(2X), then we would have 0 profit.
Here we have 50(1.95X), so we clearly lost money.

The .05X that we lost can be quantified as 50(.05X) = 2.5X
Once we know the purchase price (X) of each packet, then we can just plug in and we'll know the total loss.

We're told that the price of a "10% loss" packet = $9, so the original price = $10. We can plug that in for X...

2.5(10) = 25 dollars lost

Final Answer:
GMAT assassins aren't born, they're made,
Rich

Lets put only 100 chocolates in the question, as rest 50 did not make any difference in profit/loss

Chocolate sold at 9 made a loss of 10%, means

Cost price \(= 9*\frac{100}{90} = 10\)

50 Chocolates at 5% profit

\(= 50 * 10*\frac{105}{100} = 525\)

50 chocolates at 10% loss

= 50 * 9 = 450

Total Selling price = 525+450 = 975

Total Cost price = 100*10 = 1000

Loss = 25

Answer = C

1/3 of 150 = 50 packets

Price of 50 packets that were sold at a loss = 9 x 50 = $450

90% x Cost Price = $450
Cost Price = 450 x 10/9 = $500
Loss = 450 – 500 = -$50

150% of 500 = $525
Profit = 525 – 500 = $25

Overall profit or loss = -50 + 0 + 25 = -$25 loss