Explanation for Question 36 From the Math (Calc) Section on the Official Sat Practice Test 6
Question 36 gives us this table. 2 And then it asks us Andrew and Maria, 3 each collected six rocks. And the masses of the rocks are shown in the 4 table above the mean of the masses of the rocks that Maria collected is 5 0.1 kilogram greater than the mean of the masses of the rocks that Andrew 6 collected. What is the value of X? 7 Okay. So first we have to find the mean of 8 the masses of Andrews rocks because we know the relationship between Andrew and 9 Maria's means. So the mean is just going to be equal to 10 all of these instances, summed up divided by the number of instance instances 11 with that being six. So 2.4 plus 2.5 plus 12 3.6 plus 3.1 plus 2.5 13 plus 2.7. So for the mean 14 sub a with a meaning, 15 Andrew, we have it being equal to 16.8 divided by 16 six. So 16.8 divided by six is going to be equal to 2.8 17 kilograms. 18 Now we know that the mean of the masses of the rocks, 19 the Maria collected is 0.1 kilograms greater than Andrew's mean. 20 So mean of, um, 21 with MB Maria is equal to Andrew's mean 2.8 kilograms 22 plus 0.1 kilograms. 23 So that means that Maria's mean is 2.9 24 kilograms. Now we're getting very close. 25 So we're trying to find the value of ax. And we know that again, 26 the mean is equal to the sum of all the instances divided by the 27 number of instances. So let's rewrite that expression 28 and we'll see that we're left with only one unknown. 29 So we have 2.9 kilograms as equal to X plus 3.1 30 plus 2.7 plus 2.9 plus 3.3 31 plus 2.8...