Explanation for Question 29 From the Math (Calc) Section on the 2019 April Sat
And 29, we're told that Selena created a scale model of a plane where 2 once in a meter on the model is equal to six meters on the 3 plane, then we're told that the wingspan of the model is 10.7 4 centimeters. Now Selena wants to make a new model where one centimeter 5 is equal to three meters on the plane. 6 And we want to know how the wingspan of the new model is going 7 to compare to the wingspan of the first model. 8 So we can go ahead and use this information first to find the 9 wingspan of the actual plane in meters. 10 So if one centimeter is equal to six meters, 11 then 10.7 centimeters is going to be equal to 12 X amount of meters on the plane. 13 So if you cross multiply 10.7 times six is 14 equal to X. So X is equal to 15 64.2 meters. So the wingspan of the actual plane is 64.2 16 meters. 17 Now we can take those 64.2 meters and this new ratio that we're 18 using in order to find the wingspan of the model. 19 So we're going to set it up the same way. 20 One centimeter is now equal to three meters. 21 Now X is going to represent the wingspan of the model. 22 So X centimeters is equal to 64.2 23 meters. So if we go ahead and cross multiply 64.2 24 is equal to three X. 25 So 64.2 divided by three means that X is 26 equal to 21.4. 27 So the original model was 10.7 centimeters. 28 The new one is 21.4. 29 So the waistband of the new model is two times as long as the 30 wingspan of the first model.