Explanation for Question 30 From the Math (Calc) Section on the 2017 May Sat
Let's take a look at question 30. And if you do recall, 2 they are in order of difficulties. 3 So 30 should be one of the toughest questions on the test before it 4 starts over in level of difficulty. 5 And we get to the fear response. So this one should be a tough 6 question. Question. 30 says a biologist grows a culture of bacteria 7 as part of an experiment at the start of the experiment. 8 There are 75 bacteria in the culture. 9 So I'm going to circle that because it's important. Then we have the biologist 10 of serves that the population of bacteria doubles every 11 18 minutes, which of the following equations, 12 best models, a number N of bacteria T hours after 13 the start of the experiment. So we have exponential 14 growth type of question four that we need to know the equation for exponential 15 growth, which is, which is Y 16 equals a one plus or minus R 17 times X technically was, 18 since we know it's growth, we can delete that minus because that's everywhere. 19 Okay. So let's talk about what I read variable here means 20 Y is going to be your final, 21 your result a is your starting point or your starting value. 22 And then the parentheses here will be how much you're growing. 23 Our is the rate of growth. So the printing itself will be how much 24 you're growing. And then X is, 25 you can think about it as how often it grows. It's the time that 26 it takes to do that growth. So based on our paragraph, 27 now we can plug some, um, variables in. 28 So we know 75...