Explanation for Question 3 From the Math (Calc) Section on the 2019 October Sat
Now a number three, we're told that a store receives a shipment of 1000 2 MP3 players and four of them are defective. 3 So if we're going to write a fraction to represent the probability that you 4 have a defective phone, it would be four or not phone, 5 but MP3 player. It would be four out of a thousand, 6 right? And so we look at our answer choices and we can see that 7 what they want us to give them is a decimal instead of a fraction 8 or a percent. So all that we need to do here is take this, 9 uh, take this fraction and turn it into it's decimal. 10 And you can either do that with mental math, or just by plugging in 11 your calculator, four divided by 1000. 12 And when you do that, you get 0.004 and that's answer 13 choice a, um, 14 it's your choice. See if he chose C, then you probably chose the percentage, 15 right? Because 0.0, zero four as a percentage is 0.4%. 16 But we know that we don't want to percentage here. We just want the 17 decimal probability. And so our best answer is a.