Compartive Pie Chart Question B: Work out the number of packs of vegan sausages that were sold in May 2019

[Johnstone]

Hello, I am wondering if someone can explain the attached question '(b)'. I understand to calculate angle difference of sausages I can do 30*90/60 to find scale factor between 2015 and 2019 and find the amount of sausages for 90° but why should I multiply by (4/3)^2 to get a sum of 80 sausages? I am slightly concerned as there is no radius information attached to interpret.

 

[Dr.Peterson]

Hello, I am wondering if someone can explain the attached question '(b)'. I understand to calculate angle difference of sausages I can do 30*90/60 to find scale factor between 2015 and 2019 and find the amount of sausages for 90° but why should I multiply by (4/3)^2 to get a sum of 80 sausages? I am slightly concerned as there is no radius information attached to interpret. View attachment 37377

All I can see to do is to measure the radii. Yes, it's odd that they would tell you the angles, but not the radii; but that appears to be what's expected.

I assume you were told that the area of each chart is proportional to the actual numbers; that is not normal for pie charts, but can be appropriate.

why should I multiply by (4/3)^2 to get a sum of 80 sausages?

Are you saying that you were given a solution, and don't understand why it includes this step? Presumably they measured the radii and found they have the ratio 4/3, so the areas have the square of that ratio.