Explanation for Question 10 From the Math (No Calc) Section on the Official Sat Practice Test 6
Question 10 asks us, Jaime's preparing for a bicycle race. 2 His goal is to buy school and average of at least 280 miles per 3 week. For four weeks, he bicycle 240 miles. 4 The first week, 310 miles the second week and 320 miles the third week, 5 which inequality can be used to represent the number of miles ex Jaime could 6 bicycle on the fourth week to meet his goal. 7 So the first key word here is going to be an average of at 8 least 280 miles per week. 9 So we now know what inequality sign we're looking at because this side should 10 be what finds us the average. And it's going to have to be greater 11 than, or equal to 280 to make it at least that many miles. 12 Now, for an average, we know that we have to sum up all of 13 our different instances and then divide by the number of instances. 14 So in this case, on the top, we're going to have the number of 15 miles that he did each week divided by four, 16 because that's the total number of weeks. So we've got on top two, 17 40 plus three, 18 10 plus three, 19 20 plus X, 20 and X is that number of miles, 21 city bikes in the fourth week. So this is pretty close to our answer. 22 And we want to take a look at the answer choices and see if 23 any matchup, unfortunately they don't. 24 But if you multiply both sides of this expression by four, 25 which you can do since you do the same thing to both sides, 26 it's the same expression. So these fours will cancel out and we're left with 27 two 40 plus three, 10 plus three 20 plus 28 X is greater than or equal to 280 times four ensure 29 enough that hopefully it looks a lot more familiar. 30 If we take a look at our answer choices, that's going to be the 31 same thing as D. So we can pick that as our.