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

1. What was the percentage increase in the number of pens sold from Jan to Feb?
2. There were 160 less pens sold in Jan than in Mar. How many pens were sold in Jan?
3. The average number of pens sold from Jan to May was 174. What was the average number of pens sold in Apr and May?

(a)
Percentage increase in the number of pens from Jan to Feb
= ^{5 - 2}₂ x 100%
= ³₂ x 100%
= 150%

(b)
Difference in intervals between Mar and Jan
= 10 - 2
= 8

8 intervals → 160

1 interval → 160 ÷ 8 = 20

Number of pens sold in Jan
= 2 intervals
= 2 x 20
= 40

(c)
Total intervals from Jan to Mar
= 2 + 5 + 10
= 17

Total number of pens sold from Jan to Mar
= 17 intervals
= 17 x 20
= 340

Total number of pens sold from Jan to May
= 5 x 174
= 870

Number of pens sold from Apr to May
= 870 - 340
= 530

Average number of pens sold in Apr and May
= 530 ÷ 2
= 265

Answer(s): (a) 150%; (b) 40; (c) 265