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

1. What was the percentage decrease in the number of correction tapes sold from Aug to Sep?
2. There were 105 more correction tapes sold in Sep than in Jul. How many correction tapes were sold in Aug?
3. The average number of correction tapes sold from Jul to Nov was 173. What was the average number of correction tapes sold in Oct and Nov?

(a)
Percentage decrease in the number of correction tapes 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 → 105

1 interval → 105 ÷ 7 = 15

Number of correction tapes sold in Aug
= 10 intervals
= 10 x 15
= 150

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

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

Total number of correction tapes sold from Jul to Nov
= 5 x 173
= 865

Number of correction tapes sold from Oct to Nov
= 865 - 285
= 580

Average number of correction tapes sold in Oct and Nov
= 580 ÷ 2
= 290

Answer(s): (a) 20%; (b) 150; (c) 290