Explanation for Question 9 From the Math (Calc) Section on the 2018 March Sat
Question nine asks what was the approach? 2 Approximate storage capacity and acre feet of the reservoir at the end 3 of 1993. So first I'm just going to set up our equation. 4 So we know that the reservoir starts with 300,000 feet, 5 and we know that it's decreasing at a constant rate of 1,700 6 per year, and that's going to give us our answer. 7 So since we know we're doing from 1993 and the starting year 8 was 1928, we know that it's been 65 years. 9 So T is equal to 65. 10 So let's plug that in 300,000 minus 1,700 11 times 65, 1,700 times 12 65 is equal to when you plug it into a calculator, 13 110,500. 14 And then when we subtract, we get 189,500 15 and that's answer choice.