PSLE
The bar graph shows the number of files sold from Jul to Sep. The number of files sold is not shown on the scale.

1. What was the percentage increase in the number of files sold from Jul to Aug?
2. There were 88 less files sold in Jul than in Sep. How many files were sold in Jul?
3. The average number of files sold from Jul to Nov was 163. What was the average number of files sold in Oct and Nov?

(a)
Percentage increase in the number of files from Jul to Aug
= ^{5 - 2}₂ x 100%
= ³₂ x 100%
= 150%

(b)
Difference in intervals between Sep and Jul
= 10 - 2
= 8

8 intervals → 88

1 interval → 88 ÷ 8 = 11

Number of files sold in Jul
= 2 intervals
= 2 x 11
= 22

(c)
Total intervals from Jul to Sep
= 2 + 5 + 10
= 17

Total number of files sold from Jul to Sep
= 17 intervals
= 17 x 11
= 187

Total number of files sold from Jul to Nov
= 5 x 163
= 815

Number of files sold from Oct to Nov
= 815 - 187
= 628

Average number of files sold in Oct and Nov
= 628 ÷ 2
= 314

Answer(s): (a) 150%; (b) 22; (c) 314