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

1. What was the percentage decrease in the number of markers sold from Jul to Aug?
2. There were 80 more markers sold in Sep than in Jul. How many markers were sold in Sep?
3. The average number of markers sold from Jul to Nov was 108. What was the average number of markers sold in Oct and Nov?

(a)
Percentage decrease in the number of markers 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 → 80

1 interval → 80 ÷ 4 = 20

Number of markers sold in Sep
= 9 intervals
= 9 x 20
= 180

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

Total number of markers sold from Jul to Sep
= 17 intervals
= 17 x 20
= 340

Total number of markers sold from Jul to Nov
= 5 x 108
= 540

Number of markers sold from Oct to Nov
= 540 - 340
= 200

Average number of markers sold in Oct and Nov
= 200 ÷ 2
= 100

Answer(s): (a) 40%; (b) 180; (c) 100