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

1. What was the percentage decrease in the number of files sold from Jan to Feb?
2. There were 68 more files sold in Mar than in Jan. How many files were sold in Mar?
3. The average number of files sold from Jan to May was 195. What was the average number of files sold in Apr and May?

(a)
Percentage decrease in the number of files 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 → 68

1 interval → 68 ÷ 4 = 17

Number of files sold in Mar
= 9 intervals
= 9 x 17
= 153

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

Total number of files sold from Jan to Mar
= 17 intervals
= 17 x 17
= 289

Total number of files sold from Jan to May
= 5 x 195
= 975

Number of files sold from Apr to May
= 975 - 289
= 686

Average number of files sold in Apr and May
= 686 ÷ 2
= 343

Answer(s): (a) 40%; (b) 153; (c) 343