Explanation for Question 35 From the Math (Calc) Section on the Official Sat Practice Test 1
Question 35 says the dairy farmer uses a store, 2 a storage silo, but it's in the shape of a right circular cylinder above. 3 If the volume is 700 or 72 PI cubic yards, 4 what is the diameter of the base of the cylinder? 5 Right? So the diameter would beat this, the diameter of the circular base. 6 So in order to do this problem, we need to know the formula for 7 the volume of a cylinder, which is PI R squared, 8 the area of a circle times the height. So what we can do here 9 is first solve for R using the volume and the height. 10 And then from our, we can multiply that by two to give us the 11 diameter. So the volume is 72 PI and that's equal to PI 12 times R squared, times eight. 13 Right? So first thing I can do is cancel out the pies that are 14 on both sides and then divide by eight. 15 And when I do 72 divided by eight, 16 we should get nine, 17 I believe. Yes. So we'll get nine. 18 These cancel nine is equal to R squared. 19 So now I just need to square root. So I know that our radius 20 is equal to three. And so you might be tempted to write down three 21 here, but remember, we're looking for the diameter, 22 right? And diameter is two times the radius, 23 which will be two times three. So our diameter must be equal 24 to six.