



 
Hi Susan, There is a fixed volume of oil, 1 cubic metre, so V = 1 cu metre and dV/dt = 0 m^{3}/h. You have however differentiated π r^{2} h incorrectly. π is a constant and r^{2} h is a product so you need to use the product rule. Try to complete the problem now and write back if you need more assistance. Penny  


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