Maths Problems - 24 May 2011

1. A swimmer had to swim a distance of 50 m out in the sea. On the average, he took 1 min to swim 20 m and lost 1 min each time he was pushed back 10 m by the wave. He continued in this way for the rest of the journey. How long would it take the swimmer to swim 50m out in the sea? (1m)

2. Tank A was completely filled with water. When 2/5 of the water in tank A was poured into Tank B, it filled only 1/3 of Tank B. The capacity of the Tank B was 1.2 m3 more than that of Tank A. Find the capacity of the Tank A. (Give your answer in cubic metres.) (3m)

3. 40% of the pupils in a school were boys. 30% of the boys and 50% of the girls participated in an English Quiz. 180 boys took part in the quiz. How many girls participated in the quiz? (3m)

4. Imran, Owen and Muthu shared some Pokemon cards in the ratio of 3 : 6 : 4. Imran kept 1/5 of his cards and gave the rest of his cards to Owen and Muthu in the ratio of 1 : 3. As a result, Owen had 700 more cards than Muthu.
(a) How many cards did Imran keep for himself?(2m)
(b) Find the total number of cards Owen had after receiving the cards from Imran. (2m)

5. Jeremiah bought 4 pairs of shoes for $(3n + 8). He also bought two shirts at $3n each.
(a) What was the cost of a pair of shoes? (1m)
(b) If n = 8, how much did 2 shirts and a pair of shoes cost? (3m)

6. Mrs Chan used either butter or margarine for her cakes. The cost of butter was thrice as much as the cost of margarine. She used 60% of butter and 40% of margarine to bake cakes. She spent $220 on the butter and margarine that she had used to bake the cakes. How much would she save if she used 40% of butter and 60% of margarine instead? (5m)