What should come in place of the question mark (?) in the following mathematical statement?
\( \sqrt{19 \times 650 \div 13 + 18.5 \times 4 \times 13} = ? \)
A person goes from P to Q at a speed of 20 km/h. Then he goes from Q to R at a speed of q km/h. Finally the person goes from R to S at a speed of r km/h. The distances from P to Q, Q to R and R to S are equal. If the average speed from P to R is \( \frac{280}{11} \) km/h, and the average speed from Q to S is \( \frac{112}{3} \) km/h, then what is the value of r?
The length of each side of a cube is 4 cm. What is the volume of the cube?
The amount received after 8 years on a certain sum of money invested at the rate of 18% simple interest per annum is ₹1,220. What was the initial sum invested?