What percentage of numbers from $1$ to $70$ have squares that end in the digit $1$?

An index of $12$ shares contains,among others,the shares of Vision Power,Vision Infra,and Vision Communication with weightage of $7\%$,$13\%$,and $15\%$ respectively. What is the increase in the prices of other shares,if these three rise by $9\%$,$10\%$,and $4\%$ respectively,while the index rises by $6\%$?

Mr. Sarang invests $6 \%$ of his monthly salary,i.e.,$Rs.$ $2,100$ on insurance policies. He also invests $8 \%$ of his monthly salary on Family Mediclaim Policies and another $9 \%$ of his salary on $NSCs$. What is the total annual amount invested by Mr. Sarang?

$? \times 15 = 37.5 \%$ of $220$

The weight of a container alone is $25 \%$ of the container filled with a certain fluid. When some fluid is removed,the weight of the container and remaining fluid is $60 \%$ of the original total weight. What fractional part of the liquid has been removed?

In a class,$70 \%$ of the students read Hindi,$40 \%$ of the students are boys,and $20 \%$ of the girls do not read Hindi. What percentage of boys read Hindi?