Explanation for Question 18 From the Math (Calc) Section on the Official Sat Practice Test 10
Now for number 18, we're looking at the question right here, 2 which says that the table shows the results of a survey in which tablet 3 users were asked, how often they would watch the video advertisements 4 in order to access streaming content for free. 5 And now the question is based on that table, 6 which of the following is closest to the probability that a tablet, 7 user answers always given that the tablet user did not 8 answer never. Alright. 9 So you can see that the question they're asking us about the probability follows 10 a certain format. It says blank, 11 given that blank. And there's the given that, 12 so we need to know what goes before and what goes after, 13 because what goes before the blank goes into your numerator when 14 you write a fraction for the probability and what goes after the giving goes 15 into your, the nominator, right? 16 This is kind of like your new total, 17 your new total. 18 And we see that it says, given that the tablet user did not say 19 never. So over here is, 20 did not say never. 21 And so that's everybody right here, 22 everyone right here, everybody except for the never people. 23 And so we're simply going to add all of those percents together so that 24 we can get their combined percent. So we do the 24.3 plus the 25 13.5 plus the 30.9. 26 And we get 68.7. So like I said, 27 that's your new total? This, 28 this is your total that's relevant to the problem. 29 And so we put that number after the given in the denominator always. 30 And now, um, the question is what is the probability that the tablet user 31 answered? Always. So now we just simply need to find the always piece 32 that goes up here and we see that that number was 30.9. 33 So we'll put that in our numerator and then to find our answer, 34 we're simply going to divide 30.9 divided by 68.7 and 35 we get 0.449. 36 Right? We see that just about 0.45 making our best 37 answer C.