Explanation for Question 26 From the Math (Calc) Section on the 2019 April Sat
In 26, it says during an ice age, 2 the average annual global temperature was at least four degrees Celsius lower than the 3 modern average. If the average annual temperature of an ice age is Y degrees 4 Celsius and the modern average annual temperature is X degree Celsius, 5 which of the following must be true. So we are looking for an equation 6 that represents what the word problem is saying. 7 It can be a little bit confusing to try and pick out information from 8 the paragraph. So I always write little bullet points or little notes of information 9 that it says. So it says the average annual global temperature was 10 at least four degrees Celsius lower than the modern average. 11 So annual was at least four 12 degrees Celsius lower than the modern 13 average. Now it defines our variables. 14 So the average annual temperature is Y degrees and 15 the modern average annual temperature is X degrees. 16 So now this right here is a lot easier to look at than trying 17 to pick out information from the paragraph. 18 So I will use my notes to create the equation. 19 So the annual was at least four degrees lower than 20 the modern. So modern is X and for lower than 21 that, we would subtract the four. So now we're no we're looking for an 22 X minus four. We can get rid of B. 23 Then we also know since we have the, at least in there, 24 it's not going to be equal. We just have to figure out which sun 25 it's pointing to so we can get rid of a as well. 26 So now we just need to figure out, is it a greater than, 27 or equal to sign or a less than or equal to sign? 28 So since it says the annual was at least four degrees 29 lower, that means it's going to be modern minus four and everything 30 below that. So why is going to be every value less 31 than the modern minus four? So that means the answer is D Y 32 is less than or equal to X minus four.