Explanation for Question 7 From the Math (Calc) Section on the 2017 May Sat
Question seven says a 15 foot wire and a five foot wire where each 2 cut completely into 10 inch pieces. 3 How many more? 10 inch pieces resulted from the 15 foot wire then from 4 the five foot wire. And then they tell us the conversion between interest and 5 fit. So the first thing you want to do is since they are asking 6 for results in inches, um, 7 or that is like the last thing we need to consider. 8 When you change the feet of the wire into inches, 9 we have 15 feet and we use a unit conversion method. 10 We multiply by, um, 11 a fraction with this conversion. 12 When you use the unit conversion method, you want to have the units that 13 you want to cancel out in the bottom. 14 In this case, we want to cancel out feet and the units that you 15 want to end up with on the top, 16 in this case inches that's because when you multiply this out, 17 you want to be able to cancel out the feet. 18 So we know 12 inches is one foot. 19 The reason we can multiply by this is because 12 inches and one foot 20 is just saying one over one. They're the same thing. 21 So we're not changing any value. We're just changing the format of this 15 22 feet. Again. Now we multiply across, 23 um, if it makes it easier, 24 pretend that you have a, um, uh, one in your denominator. 25 I know you do as you multiply top one across, 26 um, before you do that though, 27 make sure you can cross out feet. Cause once I'm in numerator, 28 once in the denominator, so you have 15 times 12 29 anxious, um, over...