A person incurs a loss of 5% be selling a watch for Rs. 1140. At what price should the watch be sold to earn 5% profit.

Answer: Option C

Explanation:

Let original Cost price is x
Its Selling price = 105/100 * x = 21x/20
New Cost price = 95/100 * x = 19x/20
New Selling price = 110/100 * 19x/20 = 209x/200
[(21x/20) - (209x/200)] = 1

=> x = 200

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 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 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 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%