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

1. What was the percentage decrease in the number of folders sold from Feb to Mar?
2. There were 105 more folders sold in Mar than in Jan. How many folders were sold in Feb?
3. The average number of folders sold from Jan to May was 173. What was the average number of folders sold in Apr and May?

(a)
Percentage decrease in the number of folders 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 → 105

1 interval → 105 ÷ 7 = 15

Number of folders sold in Feb
= 10 intervals
= 10 x 15
= 150

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

Total number of folders sold from Jan to Mar
= 19 intervals
= 19 x 15
= 285

Total number of folders sold from Jan to May
= 5 x 173
= 865

Number of folders sold from Apr to May
= 865 - 285
= 580

Average number of folders sold in Apr and May
= 580 ÷ 2
= 290

Answer(s): (a) 20%; (b) 150; (c) 290