Explanation for Question 20 From the Math (Calc) Section on the Official Sat Practice Test 4
So right here in number 20, we're looking at the massively living organisms 2 in a lake being defined or rather, 3 right. So that mass is the biomass that's in the lake. 4 And then we're told that if the biomass in the lake is doubling each 5 year is everywhere. Every year we double, we 6 want to pick the graph that represents that. Right. 7 And so we can kind of make our own little graph if you're unsure 8 of what doubling looks like, we might say, 9 okay, 1, 2, 3, 4, 10 let's go by twos here. 2, 4, 6, 8, 10. 11 And then this is 1, 2, 3, 4, 12 right? So let's say we started at a one and 13 then after one, right, we double. 14 So then we're at two. So this will be two. 15 And then we double up. So then we're at four and then we double 16 up from there. So then we're at eight. And so you see that, 17 right? 18 We're not going up by the same number. Every time, 19 one time we went up by two, one, then we went up by two. 20 Then we went up by six. So if you're doubling the amount that you're 21 increasing by gets bigger over time. In other words, 22 this is not a linear function, but an exponential function. 23 Right? So anything that's align is a constant increase. 24 So a can go, um, 25 D can also go as well, right? Because D shows the biomass and never 26 changing. It looks like the biomass is always approximately 1.75 27 here. Right? So that shows no increase, 28 nothing going up. And so if we're deciding between B and C, 29 right, we can see that first and B, 30 we have som...