Brad has a cylindrical barrel with radius 10 inches and height 15 inches. He wants to fill it from a well, using a bucket in the shape of a hemisphere with a radius of 10 inches. How many trips must Brad make to the well in order to fill the barrel?
First, we want to find the volume of the barrel. The formula for the volume of a cylinder is h* π * r^2. Substituting 15 in for h and 10 in for r, we get that the volume of the barrel is 1500π. Now, we must find the area fo the bucket. The formula for the volume of a hermisphere is (2/3)* π * r^3. Substituting 10 in for r, we get that the volume of the bucket is 2000/3π. We divide 1500π by 2000/3π to get 9/4, but Brad can't make 1/4 of a trip to the well and get water, so the answer is 3 trips.