can you explain questions 4-6 step by step

4 . Oil spilled from a ruptured tanker spreads in a circle whose area increases at constant rate of 6km2/h. How fast is the radius of the spill increasing when the area is 9km?? Circle It ( A = Are de = 6 km/h de = 211r . dr r = 9 15m dr 6 km'/4 = 271 ( 9) (at) df = ? 5. A spherical balloon is inflated so that its volume is increasing at a constant rate of 3f+3/min. How fast is the diameter increasing when the radius is Ift? d odv = 38+ 3 / min du = 4 1r ? dr r = ift d+ de 3 = 4 TT ( 1 ) 2 . dr 6. A spherical balloon is to be deflated so that its radius decreases at a constant rate of 15cm/min. At what rate must the air be removed when the radius is 9cm? Answers 1. 12f+2/min 2. -20ncm3/s 3. 180rift2/s 4. 2 TE = km/h 5 . ft / min 6. 4860 cm 3 / min