The answer is below.
Work Step by Step
a) We see from the ratio that 3/8 of students are male. Since there are around 1200 students, we guess that 450 are male. We check: $ = (1096)(3/8) = 411$ b) The square footage is between twice and three times as much, so we guess that twice to three times the amount of fertilizer is needed. We guess 35 pounds. We check: $= 3000 (15/1200) = 37.5$ c) It is 3/2 as much money, so we need 3/2 the amount of the investment. We guess 7500 dollars, which is the answer. d) Its width is about 3/8 of the length. The length is almost 80, so the width must be a bit less than 30. We guess 28. We now check: $ 70(3/8) = 26.25$