PSLE
A company offered 100 sandwich makers at 30% discount during a 7-day sale. The line graph shows the number of sandwich makers left unsold at the end of each day.

1. On which day was the most number of sandwich makers sold? Give your answer in this format. (Eg Day 1)
2. What percentage of the 100 sandwich makers were sold in the first four days of the sale?
3. During the sale, the discounted price of the sandwich makers was $91. After the sale, the remaining sandwich makers were sold without discount. What was the total amount of money collected from selling all 100 sandwich makers?

(a)
The steepest line is from Day 2 to Day 3.

On Day 3, the most number of sandwich makers was sold.

(b)
Number of sandwich makers that were left at Day 4 = 60

Number of sandwich makers that were sold for the first four days
= 100 - 60
= 40

Percentage of sandwich makers that were sold for the first four days
= ⁴⁰₁₀₀ x 100%
= 40%

(c)
Number of sandwich makers that were left at the end of the sale = 20

Number of sandwich makers that were sold during the sale
= 100 - 20
= 80

Total amount that collected from the sandwich makers sold
= 80 x 91
= $7280

Price of each sandwich maker after 30% discount 
= 100% - 30%
= 70%

70% of the price = 91
1% of the price = 91 ÷ 70 = 1.3
100% of the price = 100 x 1.3 = 130

Amount collected from selling the remaining sandwich makers
= 20 x 130
= $2600

Total amount collected from selling all the 100 sandwich makers
= 7280 + 2600
= $9880

Answer(s): (a) Day 3; (b) 40%; (c) $9880