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

1. What was the percentage decrease in the number of highlighters sold from Jan to Feb?
2. There were 64 more highlighters sold in Mar than in Jan. How many highlighters were sold in Mar?
3. The average number of highlighters sold from Jan to May was 186. What was the average number of highlighters sold in Apr and May?

(a)
Percentage decrease in the number of highlighters 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 → 64

1 interval → 64 ÷ 4 = 16

Number of highlighters sold in Mar
= 9 intervals
= 9 x 16
= 144

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

Total number of highlighters sold from Jan to Mar
= 17 intervals
= 17 x 16
= 272

Total number of highlighters sold from Jan to May
= 5 x 186
= 930

Number of highlighters sold from Apr to May
= 930 - 272
= 658

Average number of highlighters sold in Apr and May
= 658 ÷ 2
= 329

Answer(s): (a) 40%; (b) 144; (c) 329