Question : The percentage of nitrogen in air is about ______ by volume.

Option 1: 76%

Option 2: 78%

Option 3: 82%

Option 4: 74%

Question : Find the value of $\frac{\frac{1}{3} + \frac{1}{4}[\frac{2}{5}-\frac{1}{2}]}{1\frac{2}{3} \text{of} \frac{3}{4}-\frac{3}{4} \text{of} \frac{4}{5}}$.

Option 1: $\frac{37}{78}$

Option 2: $\frac{37}{13}$

Option 3: $\frac{74}{78}$

Option 4: $\frac{74}{13}$

Question : What is the value of $\frac{43 \times 2–21\ \text {of}\ 4}{28–7\ \text {of}\ 5+9}$?

Option 1: 3

Option 2: 2

Option 3: 4

Option 4: 1

Question : The radius of a circle is increased by 10%. The percentage increase in its area is:

Option 1: 10%

Option 2: 11%

Option 3: 20%

Option 4: 21%

Question : The radius of a sphere is doubled. The percentage increase in its surface area is ______.

Option 1: 75%

Option 2: 100%

Option 3: 300%

Option 4: 400%