Explanation for Question 6 From the Math (Calc) Section on the 2020 March Sat
So question number six tells us that a field has a perimeter of 960 2 feet. And that's the following, which is closest to the perimeter in meters. 3 So essentially what we're doing here is called units analysis, 4 where we're taking an original unit, 5 the feet and trying to convert it into a different unit in this case 6 meters. So let's start with the nine 60, 7 we have 960 feet and we want to change it into meters and they 8 give us right here, a conversion where we go one foot is really 9 0.3, 0, 4, 8 of a meter. 10 And we're going to use that conversion factor to turn our feet into meters 11 and the ultimate goal. And this is something that's normally taught in chemistry sometimes 12 is to get rid of the feet and end up with the unit of 13 meters. So what I need to do is put my units so that my 14 feet will cancel. 15 Since I start with my feet in the numerator. When I write out this, 16 uh, conversion factor as a fraction, 17 I need my feet to be in the denominator. 18 So I'll rewrite. It is one foot is equal to 0.3, 19 0 4 8 meters. 20 We can now see that if I were to multiply across and we can 21 even pretend that the numbers don't exist here. But just imagine that I was 22 multiplying across looking at the units, 23 we would get feet, times, meters, 24 over feet, and our feet would cancel. 25 And it would just leave us with the units of meters, which is what 26 we want. So that shows me that I've set up my conversion correctly. 27 These feet would cancel. And so all I have to do here is nine 28 60 times 0.3048. 29 So nine 60 times 0.3048. 30 And when I plugged that into the calculator, you get about 292, 31 which is really close to the answer B 290. 32 So the ultimate goal, when you think about unit analysis is finding a way 33 to cancel out the units that you're no longer interested in in this case 34 feet and introduce units that you are interested in in this case, 35 the meters.