PSLE
A company offered 180 kettles at 10% discount during a 7-day sale. The line graph shows the number of kettles left unsold at the end of each day.

1. On which day was the most number of kettles sold? Give your answer in this format. (Eg Day 1)
2. What percentage of the 180 kettles were sold in the first four days of the sale?
3. During the sale, the discounted price of the kettles was $72. After the sale, the remaining kettles were sold without discount. What was the total amount of money collected from selling all 180 kettles?

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

On Day 3, the most number of kettles was sold.

(b)
Number of kettles that were left at Day 4 = 90

Number of kettles that were sold for the first four days
= 180 - 90
= 90

Percentage of kettles that were sold for the first four days
= ⁹⁰₁₈₀ x 100%
= 50%

(c)
Number of kettles that were left at the end of the sale = 40

Number of kettles that were sold during the sale
= 180 - 40
= 140

Total amount that collected from the kettles sold
= 140 x 72
= $10080

Price of each kettle after 10% discount 
= 100% - 10%
= 90%

90% of the price = 72
1% of the price = 72 ÷ 90 = 0.8
100% of the price = 100 x 0.8 = 80

Amount collected from selling the remaining kettles
= 40 x 80
= $3200

Total amount collected from selling all the 180 kettles
= 10080 + 3200
= $13280

Answer(s): (a) Day 3; (b) 50%; (c) $13280