The length x of a rectangle is increasing at the rate of 3 cm/minute and the width y is increasing at the rate of 6 cm/minute. When x =5 cm and y = 5 cm, find the ratio of rates of change of area to that of the perimeter with respect to time.
Answer & explanation
Correct answer: option 4
dA/dt = x(dy/dt)+y(dx/dt)
dP/dt = 2(dx/dt +dy/dt)