A shopkeeper expects a gain of 45/2 % on his C.P. If his sale was Rs. 392, then find his profit.

Answer: Option D

Explanation:

In this type of question, we will first find total C.P. of items, then total S.P. of items, then we will get gain or loss. From which we can easily calculate its percentage.

So lets solve it now.

$$\begin{aligned} \text{So, C.P. of 1st transistor = }\\ \left( \frac{100}{120} * 840 \right) = 700 \\ \text{C.P. of 2nd transistor = }\\ \left( \frac{100}{96} * 960 \right) = 1000 \\ \text{Total C.P. = 1700 }\\ \text{Total S.P. = 1800 }\\ \text{Gain = 1800 - 1700 = 100}\\ \text{Gain% = } \left( \frac{100}{1700} * 100 \right) \\ = 5\frac{15}{17}\% \end{aligned}$$

Answer: Option A

Explanation:

Please note in this type of questions, get the value of 1 kg to solve this question, lets solve it.

C.P. of 1 Kg = 420/70 = Rs. 6
Selling Price = 6.50
Gain = Rs. 0.50

$$\begin{aligned} Gain\% = \frac{.50}{6}*100 \\ = 8\frac{1}{3}\% \end{aligned}$$

Answer: Option B

Explanation:

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

Answer: Option B

Explanation:

Let the cost price = Rs 100
then, Marked price = Rs 135

Required gain = 8%,
So Selling price = Rs 108
Discount = 135 - 108 = 27

Discount% = (27/135)*100 = 20%

Answer: Option A

Explanation:

Suppose he bought 5 kg and 3 kg of tea.
Cost Price = Rs. (5 x 18 + 3 x 20) = Rs. 150.
Selling price = Rs. (8 x 21) = Rs. 168.
Profit = 168 - 150 = 18

So, Profit % = (18/150) * 100 = 12%