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

1. What was the percentage decrease in the number of staplers sold from Jan to Feb?
2. There were 72 more staplers sold in Mar than in Jan. How many staplers were sold in Mar?
3. The average number of staplers sold from Jan to May was 192. What was the average number of staplers sold in Apr and May?

(a)
Percentage decrease in the number of staplers 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 → 72

1 interval → 72 ÷ 4 = 18

Number of staplers sold in Mar
= 9 intervals
= 9 x 18
= 162

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

Total number of staplers sold from Jan to Mar
= 17 intervals
= 17 x 18
= 306

Total number of staplers sold from Jan to May
= 5 x 192
= 960

Number of staplers sold from Apr to May
= 960 - 306
= 654

Average number of staplers sold in Apr and May
= 654 ÷ 2
= 327

Answer(s): (a) 40%; (b) 162; (c) 327