1. The length of a rectangle is increasing at a rate of7cm/s and its width is increasing at a rate of8cm/s. When the length is15cm and the width is9cm, how fast is the area of the rectangle increasing?
1b. A cylindrical tank with radius 5 m is being filled with water at a rate of 4 m3/min. How fast is the height of the water increasing?
1c.The radius of a sphere is increasing at a rate of 3 mm/s. How fast is the volume increasing when the diameter is 80mm?