This blog is managed by Song Hock Chye, author of Improve Your Thinking Skills in Maths (P1-P3 series), which is published and distributed by EPH.

## Friday, April 25, 2008

### Ai Tong School P5 SA1 2006 Math (Q45)

At Ai Tong Restaurant, the charge for the buffet lunch per person is \$15. For every group of 10 people, the 11th person does not have to pay.

(a) What will be the total charge for a party of 23 people?
(b) How many people are there in the group if the bill comes up to \$720?

Solution

10 people ----- 10 x \$15 = \$150
11th person ----- free
1 group of 11 ----- \$150

(a) What will be the total charge for a party of 23 people?

23 people ----- 2 groups of 11 people + 1 individual
2 groups of 11 ----- 2 x \$150 = \$300
1 individual ----- \$15
Total ----- \$300 + \$15 = \$315

Answer: The charge for a party of 23 people is \$315.

(b) How many people are there in the group if the bill comes up to \$720?

For every \$150 ----- 11 people
\$720 ----- \$600 + \$120
\$600 ----- \$600 divided by \$150 = 4 (groups of 11 people)
\$120 ----- \$120 divided by \$15 = 8 individuals

Therefore, \$720 ----- 4 groups of 11 people + 11 individuals
(4 x 11) + 8
= 44 + 8
= 52

Answer: There are 52 people if the bill comes up to \$720.