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 Feb to Mar?
2. There were 77 more highlighters sold in Mar than in Jan. How many highlighters were sold in Feb?
3. The average number of highlighters sold from Jan to May was 161. What was the average number of highlighters sold in Apr and May?

(a)
Percentage decrease in the number of highlighters from Feb to Mar
= ^{10 - 8}₁₀ x 100%
= ²₁₀ x 100%
= 20%

(b)
Difference in the number of intervals between Mar and Jan
= 8 - 1
= 7

7 intervals → 77

1 interval → 77 ÷ 7 = 11

Number of highlighters sold in Feb
= 10 intervals
= 10 x 11
= 110

(c)
Total intervals from Jan to Mar
= 1 + 10 + 8
= 19

Total number of highlighters sold from Jan to Mar
= 19 intervals
= 19 x 11
= 209

Total number of highlighters sold from Jan to May
= 5 x 161
= 805

Number of highlighters sold from Apr to May
= 805 - 209
= 596

Average number of highlighters sold in Apr and May
= 596 ÷ 2
= 298

Answer(s): (a) 20%; (b) 110; (c) 298