Explanation for Question 13 From the Math (No Calc) Section on the 2017 April Sat
Question 13 says the number of people who go to a swimming pool can 2 be modeled by the function G above where C is a constant and T 3 is the air temperature in degrees. Fahrenheit for T is less than, 4 or greater than 60, 70, 5 and less than a hundred. If 350 people are predicted to go to the 6 pool. When the temperature is 90 degrees Fahrenheit, 7 what is the value of C? So we've been given this equation at the 8 top here, as well as numbers to plug in. 9 So we know that GFT is equal to 350 and that T is 10 equal to 90. So I'm just going to start by rewriting this equation, 11 plugging in this information. So this becomes three 50 is 12 equal to five times, 13 seven times 90 minus 12 C over 14 two minus 25. 15 So the first thing I'm going to do is add 25 to both sides 16 and then multiply both sides by two. 17 So that gives me 350 plus 25 is 3 75, 375. 18 Times two is equal to 19 750. So now our equation is 750 20 is equal to five times, 21 seven times 90 minus 12 C. 22 The next thing I can do is I can distribute the five. 23 So this becomes 750 is equal to five times seven, 24 which is 35 times 90 minus 12 times five 25 or 60 C 35 26 times 90 is equal to 3,150. 27 So I can then rewrite this equation as such next. 28 I'm going to add 60 C to both sides and subtract 750 C. 29 So 60 C is equal to 3,150 30 minus 750. 31 And that right side of the equation is just equal to 2,400. 32 And then I can divide both sides by 60 to get C is equal 33 to 40. And that's our final answer. 34 So we know that the answer is B.