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

1. What was the percentage increase in the number of highlighters sold from Aug to Sep?
2. There were 57 more highlighters sold in Jul than in Aug. How many highlighters were sold in Sep?
3. The average number of highlighters sold from Jul to Nov was 123. What was the average number of highlighters sold in Oct and Nov?

(a)
Percentage increase in the number of highlighters sold from Aug to Sep
= ^{8 - 2}₂ x 100%
= ⁶₂ x 100%
= 300%

(b)
Difference in intervals between Jul and Aug
= 5 - 2
= 3

3 intervals → 57

1 interval → 57 ÷ 3 = 19

Number of highlighters sold in Sep
= 8 intervals
= 8 x 19
= 152

(c)
Total intervals from Jul to Sep
= 5 + 2 + 8
= 15

Total number of highlighters sold from Jul to Sep
= 15 intervals
= 15 x 19
= 285

Total number of highlighters sold from Jul to Nov
= 5 x 123
= 615

Number of highlighters sold from Oct to Nov
= 615 - 285
= 330

Average number of highlighters sold in Oct and Nov
= 330 ÷ 2
= 165

Answer(s): (a) 300%; (b) 152; (c) 165