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

1. What was the percentage decrease in the number of pencils sold from Jul to Aug?
2. There were 44 more pencils sold in Sep than in Jul. How many pencils were sold in Sep?
3. The average number of pencils sold from Jul to Nov was 153. What was the average number of pencils sold in Oct and Nov?

(a)
Percentage decrease in the number of pencils 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 pencils sold in Sep
= 9 intervals
= 9 x 11
= 99

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

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

Total number of pencils sold from Jul to Nov
= 5 x 153
= 765

Number of pencils sold from Oct to Nov
= 765 - 187
= 578

Average number of pencils sold in Oct and Nov
= 578 ÷ 2
= 289

Answer(s): (a) 40%; (b) 99; (c) 289