What is the difference between the average of books sold by stores A and E together and average of books sold by stores C and D together?
Show Hint
To compare averages from pie charts, always calculate the individual values first using the total and then compute the mean. Don’t forget to subtract carefully!
From the pie chart:
Total number of books = 1100
Store A = 18% of 1100 = 198
Store E = 22% of 1100 = 242
Average of A and E = \dfrac{198 + 242}{2} = \dfrac{440}{2} = 220
Store C = 16% of 1100 = 176
Store D = 32% of 1100 = 352
Average of C and D = \dfrac{176 + 352}{2} = \dfrac{528}{2} = 264
Now, the difference = 264 - 220 = \boxed{44}