PSLE
The bar graph shows the number of notebooks sold from Jan to Mar. The number of notebooks sold is not shown on the scale.

1. What was the percentage increase in the number of notebooks sold from Feb to Mar?
2. There were 30 more notebooks sold in Jan than in Feb. How many notebooks were sold in Mar?
3. The average number of notebooks sold from Jan to May was 98. What was the average number of notebooks sold in Apr and May?

(a)
Percentage increase in the number of notebooks sold from Feb to Mar
= ^{8 - 2}₂ x 100%
= ⁶₂ x 100%
= 300%

(b)
Difference in intervals between Jan and Feb
= 5 - 2
= 3

3 intervals → 30

1 interval → 30 ÷ 3 = 10

Number of notebooks sold in Mar
= 8 intervals
= 8 x 10
= 80

(c)
Total intervals from Jan to Mar
= 5 + 2 + 8
= 15

Total number of notebooks sold from Jan to Mar
= 15 intervals
= 15 x 10
= 150

Total number of notebooks sold from Jan to May
= 5 x 98
= 490

Number of notebooks sold from Apr to May
= 490 - 150
= 340

Average number of notebooks sold in Apr and May
= 340 ÷ 2
= 170

Answer(s): (a) 300%; (b) 80; (c) 170