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 decrease in the number of pens sold from Jan to Feb?
2. There were 60 more pens sold in Mar than in Jan. How many pens were sold in Mar?
3. The average number of pens sold from Jan to May was 97. What was the average number of pens sold in Apr and May?

(a)
Percentage decrease in the number of pens from Jan to Feb
= ^{5 - 3}₅ x 100%
= ²₅ x 100%
= 40%

(b)
Difference in the number of intervals between Mar and Jan
= 9 - 5
= 4

4 intervals → 60

1 interval → 60 ÷ 4 = 15

Number of pens sold in Mar
= 9 intervals
= 9 x 15
= 135

(c)
Total intervals from Jan to Mar
= 5 + 3 + 9
= 17

Total number of pens sold from Jan to Mar
= 17 intervals
= 17 x 15
= 255

Total number of pens sold from Jan to May
= 5 x 97
= 485

Number of pens sold from Apr to May
= 485 - 255
= 230

Average number of pens sold in Apr and May
= 230 ÷ 2
= 115

Answer(s): (a) 40%; (b) 135; (c) 115