Write the following statements using the symbol of variation.

(1) Circumference (c) of a circle is directly proportional to its radius (r).

(2) Consumption of petrol (I) in a car and distance traveled by that car (D) are in direct variation.

Complete the following table considering that the cost of apples and their number are in direct variation.

If and whenm=154, n=7. Find the value of m, when n=14.

If n varies directly as m, complete the following table.

y varies directly as the square root of x. When x = 16, y = 24. Find the constant of variation and equation of variation.