If $11$ mangoes are bought for $Rs. 10$ and sold at $10$ for $Rs. 11$,what is the gain or loss percentage (in $\%$)?

$A$ person sells taperecorders at $Rs. 1134$ each after giving a discount of $19 \%$ on the marked price. Had he not given the discount,he would have earned a profit of $40 \%$ on the cost price. The cost price of each taperecorder is (in $Rs.$)

Mahesh purchased $25\, kg$ of rice at $Rs. 32$ per $kg$ and $15\, kg$ of rice at $Rs. 36$ per $kg.$ He mixed the two varieties of rice and sold it at $Rs. 40.20$ per $kg.$ What is the percent profit earned (in $\%$)?

$A$ shopkeeper sold a $TV$ set for $Rs. 17940$ with a discount of $8 \%$ and earned a profit of $19.6 \%$. What would have been the percentage of profit earned if no discount was offered (in $\%$)?

Arun purchased $30 \, kg$ of wheat at the rate of $Rs. \, 11.50$ per $kg$ and $20 \, kg$ of wheat at the rate of $Rs. \, 14.25$ per $kg$. He mixed the two and sold the mixture. Approximately at what price per $kg$ should he sell the mixture to make $30 \%$ profit? (in $Rs.$)

$A$ person sells $36$ oranges for $₹ 1$ and makes a loss of $4 \%$. Find how many oranges per $₹ 1$ should be sold to have a gain of $8 \%$.