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

1. What was the percentage decrease in the number of pencils sold from Feb to Mar?
2. There were 70 more pencils sold in Mar than in Jan. How many pencils were sold in Feb?
3. The average number of pencils sold from Jan to May was 138. What was the average number of pencils sold in Apr and May?

(a)
Percentage decrease in the number of pencils 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 → 70

1 interval → 70 ÷ 7 = 10

Number of pencils sold in Feb
= 10 intervals
= 10 x 10
= 100

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

Total number of pencils sold from Jan to Mar
= 19 intervals
= 19 x 10
= 190

Total number of pencils sold from Jan to May
= 5 x 138
= 690

Number of pencils sold from Apr to May
= 690 - 190
= 500

Average number of pencils sold in Apr and May
= 500 ÷ 2
= 250

Answer(s): (a) 20%; (b) 100; (c) 250