Question

a company sells circular mirrors. the price P pounds is proportional to the square of its radius r cm. a mirror with radius 20cm has a price of £36. find a formula for p in terms of r

Answer 1

P = 0.09r²

Explanation:

Price, p is proportional to the square of its radius, r

P = k*r²

a mirror with radius 20cm has a price of £36

P = k * r²

36 = k * 20²

36 = k * 400

36 = 400k

k = 36/400

k = 0.09

Substitute the value of k into the equation:

P = k * r²

P = 0.09 * r²

P = 0.09r²