PSLE
The bar graph shows the number of post-it pads sold from Jul to Sep. The number of post-it pads sold is not shown on the scale.

1. What was the percentage decrease in the number of post-it pads sold from Aug to Sep?
2. There were 91 more post-it pads sold in Sep than in Jul. How many post-it pads were sold in Aug?
3. The average number of post-it pads sold from Jul to Nov was 147. What was the average number of post-it pads sold in Oct and Nov?

(a)
Percentage decrease in the number of post-it pads 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 → 91

1 interval → 91 ÷ 7 = 13

Number of post-it pads sold in Aug
= 10 intervals
= 10 x 13
= 130

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

Total number of post-it pads sold from Jul to Sep
= 19 intervals
= 19 x 13
= 247

Total number of post-it pads sold from Jul to Nov
= 5 x 147
= 735

Number of post-it pads sold from Oct to Nov
= 735 - 247
= 488

Average number of post-it pads sold in Oct and Nov
= 488 ÷ 2
= 244

Answer(s): (a) 20%; (b) 130; (c) 244