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

1. What was the percentage decrease in the number of staplers sold from Aug to Sep?
2. There were 77 more staplers sold in Sep than in Jul. How many staplers were sold in Aug?
3. The average number of staplers sold from Jul to Nov was 133. What was the average number of staplers sold in Oct and Nov?

(a)
Percentage decrease in the number of staplers 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 → 77

1 interval → 77 ÷ 7 = 11

Number of staplers sold in Aug
= 10 intervals
= 10 x 11
= 110

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

Total number of staplers sold from Jul to Sep
= 19 intervals
= 19 x 11
= 209

Total number of staplers sold from Jul to Nov
= 5 x 133
= 665

Number of staplers sold from Oct to Nov
= 665 - 209
= 456

Average number of staplers sold in Oct and Nov
= 456 ÷ 2
= 228

Answer(s): (a) 20%; (b) 110; (c) 228