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 Aug to Sep?
2. There were 126 more rulers sold in Sep than in Jul. How many rulers were sold in Aug?
3. The average number of rulers sold from Jul to Nov was 150. What was the average number of rulers sold in Oct and Nov?

(a)
Percentage decrease in the number of rulers from Aug to Sep
= ^{10 - 8}₁₀ x 100%
= ²₁₀ x 100%
= 20%

(b)
Difference in the number of intervals between Sep and Jul
= 8 - 1
= 7

7 intervals → 126

1 interval → 126 ÷ 7 = 18

Number of rulers sold in Aug
= 10 intervals
= 10 x 18
= 180

(c)
Total intervals from Jul to Sep
= 1 + 10 + 8
= 19

Total number of rulers sold from Jul to Sep
= 19 intervals
= 19 x 18
= 342

Total number of rulers sold from Jul to Nov
= 5 x 150
= 750

Number of rulers sold from Oct to Nov
= 750 - 342
= 408

Average number of rulers sold in Oct and Nov
= 408 ÷ 2
= 204

Answer(s): (a) 20%; (b) 180; (c) 204