Maths Problems 7 Aug 09

1. Joanne had 20-cent coins and 50-cent coins in a box. The percentage of the number of 20-cent coins was 40% of the total number of coins Joanne had. Joanne took out ten 50-cent coins and put in 20-cent coins of the same value. The percentage of the number of 20-cent coins became 50% of the total number of coins Joanne had. What was the amount of money in the box?

2. Last year 20% of the people who visited an IT show were children. 3/5 of the adults were men and the rest were women. This year, the number of children who visited the IT show has increased 10% from last year and there are 256 women more than children. The number of adults who visited the IT show remained the same but now 1/3 of the adults were women.
a) find the ratio of the number of children to the number of men to the number of the women who attended the IT show last year. (2m)
b) find the total number of people who visited the IT show this year. (3m)

3. Mr Raju was asked to deliver 1600 boxes of biscuits to Mr Lau. For every box of biscuits safely delivered, Mr Lau paid him 60 cents. But Mr Raju had to pay $1.20 for every box of biscuits damaged during transportation. If Mr Lau paid Mr Raju $927.60 for the job, how many boxes of biscuits were damaged during the journey? (5m)

4. Michael had 750 local and foreign stamps. He gave 3/4 of his local stamps and 1/3 of his foreign stamps to his best friend. He then had 250 stamps left. How many foreign stamps did he have at first? (5m)

5. Clark and Kent have some money. If Clark spends $120 a day and Kent spends
$40 a day, Clark will have $280 left while Kent will have spent all his money. If Clark spends $40 a day and Kent spends $120 a day, Clark will have $600 left when Kent has spent all his money.
(a) How much money does Kent have? (3m)
(b) How much money does Clark have? (2m)