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

1. What was the percentage decrease in the number of rulers sold from Jul to Aug?
2. There were 44 more rulers sold in Sep than in Jul. How many rulers were sold in Sep?
3. The average number of rulers sold from Jul to Nov was 93. What was the average number of rulers sold in Oct and Nov?

(a)
Percentage decrease in the number of rulers 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 → 44

1 interval → 44 ÷ 4 = 11

Number of rulers sold in Sep
= 9 intervals
= 9 x 11
= 99

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

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

Total number of rulers sold from Jul to Nov
= 5 x 93
= 465

Number of rulers sold from Oct to Nov
= 465 - 187
= 278

Average number of rulers sold in Oct and Nov
= 278 ÷ 2
= 139

Answer(s): (a) 40%; (b) 99; (c) 139