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

1. What was the percentage decrease in the number of folders sold from Jul to Aug?
2. There were 68 more folders sold in Sep than in Jul. How many folders were sold in Sep?
3. The average number of folders sold from Jul to Nov was 177. What was the average number of folders sold in Oct and Nov?

(a)
Percentage decrease in the number of folders from Jul to Aug
= ^{5 - 3}₅ x 100%
= ²₅ x 100%
= 40%

(b)
Difference in the number of intervals between Sep and Jul
= 9 - 5
= 4

4 intervals → 68

1 interval → 68 ÷ 4 = 17

Number of folders sold in Sep
= 9 intervals
= 9 x 17
= 153

(c)
Total intervals from Jul to Sep
= 5 + 3 + 9
= 17

Total number of folders sold from Jul to Sep
= 17 intervals
= 17 x 17
= 289

Total number of folders sold from Jul to Nov
= 5 x 177
= 885

Number of folders sold from Oct to Nov
= 885 - 289
= 596

Average number of folders sold in Oct and Nov
= 596 ÷ 2
= 298

Answer(s): (a) 40%; (b) 153; (c) 298