In a certain store, the profit is 320% of the cost. If the cost increases by 25% but the selling price remains constant, approximately what percentage of the selling price is the profit

Answer: Option C

Explanation:

Friends, we know we will need gain amount to get gain percent, right. So lets get gain first.

Let the cost price of 1 pen is Re 1
Cost of 8 pens = Rs 8
Selling price of 8 pens = 12
Gain = 12 - 8 = 4

\begin{aligned}
Gain\% = \left( \frac{Gain}{Cost} * 100 \right)\% \\
= \left( \frac{4}{8} * 100 \right)\% = 50\%
\end{aligned}

Answer: Option D

Explanation:

85 : 9 = 105 : x
x= (9×105/85)
= Rs 11.81

Answer: Option B

Explanation:

Let the C.P. = x,
Then S.P. = (120/100)x = 6x/5
New S.P. = 2(6x/5) = 12x/5

Profit = 12x/5 - x = 7x/5

Profit% = (Profit/C.P.) * 100
=> (7x/5) * (1/x) * 100 = 140 %

Answer: Option C

Explanation:

From the question it is clear that, Gain is 20%
From 1, it is clear that S.P. - C.P. = 40, so it is sufficient to get answer.
While 2 is not sufficient to get answer.

Answer: Option B

Explanation:

\begin{aligned}
Gain\% = \\ \left( \frac{(100 + \text{common gain}\%)^2}{100} - 100 \right)\% \\
= \left( \frac{(100 + 10)^2}{100} - 100 \right)\% \\
= \left( \frac{12100 - 10000}{100}\right)\% \\
= 21\%

\end{aligned}