University:
University of Cambridge
Course:
0580 IGCSE | Mathematics
Academic year:

2023
Views:

348

Pages:

3
Author:

Lawak A

Critical Considerations in Comparing and Scaling Answers The way to solve a value comparison problem is by : a. Determining the unit value This is done by determining the unit value of the quantities being compared, and then multiplying it by the quantity in question. b. Writing a value comparison Performed by direct comparison between two or more states Suppose two quantities A and B are known. Since like-for-like comparison applies, : Based on the relationship obtained : Sample Problem: 1. A vehicle can travel 24 km by consuming 2 liters of gasoline. How many liters of gasoline are needed to travel 60 km? Answer: Method 1: 2 liters of gasoline can travel 24 km 1 liter of gasoline can travel 12 km So to travel 60 km, 60 liters of gasoline are needed: 12 = 5 liters. Method 2: A table is made as follows: The calculation is done with : So to travel 60 km, 60 liters of gasoline are needed: 12 = 5 liters. 2. 1 dozen shirts were purchased for Rp 480,000. What is the price of 15 pieces of the same shirt? Answer: Method 1: 1 dozen shirts costs Rp 480,000. 1 shirt costs Rp 480,000.00 : 12 = Rp 40,000.00 So the price of 15 pieces of clothes is 15 x Rp 40,000.00 = Rp 600,000.00 Method 2: A table is created as follows: The calculation is done with : So the price of 15 pieces of clothes is 15 x Rp 40,000.00 = Rp 600,000.00 Now you have learned the material of comparison worth, there are even 2 ways to answer the questions, please choose which alternative you consider easy, of course it's not difficult right? 4. Inverse Value Comparison An inverse value comparison deals with comparing two states where if one quantity increases/decreases then the other quantity decreases/increases. Problems related to inverse comparison include: • Number of workers and the time it takes to complete the job (for the same job) • • • Speed with travel time (for the same distance) Number of livestock and time to finish the diet (for the same amount of fodder) And so on Suppose two quantities A and B are known Since inverse value comparison applies, : Based on the relationship obtained : Sample Problem: 1. A job will be completed in 42 days if done by 12 people. How long will the same job take if it is done by 14 people? Answer: A table is created as follows: The inverse value comparison calculation is done by reversing one of the segments: So if the work is done by 14 workers, it will be completed in 36 days. 2. The distance from city A to city B is equal to the distance from city B to city C. If AB can be traveled at 40 km/h for 10 hours, how much speed should be added if the distance BC will be traveled for 8 hours? Answer: A table is created as follows: The inverse value comparison calculation is done by reversing one of the segments: The speed to be added is 50 - 40 = 10 km/h.