1. Denzel, Eugene and Farhan bought a packet of marbles. Denzel received 145 marbles.Farhan received 30% less marbles than Eugene. Later,Denzel gave 68 marbles to Eugene and Farhan to share. After that, Farhan still had 30% fewer marbles than Eugene. The number of marbles Eugene had increased by 25%. How many marbles were there in the packet at first?
2. A music store collected $1 680 from the sale of headphones, CDs and DVDs. The ratio of the amount of money collected from the CDs to the amount collected from the DVDs to the amount collected from the headphones was 5 : 6 : 3. The CDs were sold at 2 for $25.
The number of CDs sold was three times the number of DVDs sold.
The number of headphones sold was 50% of the number of DVDs sold.
( a ) How many DVDs did the store sell?
( b ) If Mr Yong had $1125, how many headphones could he buy?
3. The ratio of the number of adults to the number of children in a housing estate is 3 : 8. The ratio of the number of boys to the number of girls is 2 : 5. There are 960 fewer boys than girls in the housing estate. How many more adults than boys are there in the housing estate?
4. Tan, Lim and Wong had some pens to sell. Tan had the least number of pens. Wong’s number of pens was 30% less than Lim’s. After Tan and Lim had each sold 50% of their pens, Lim had 95 more pens than Tan. If the three men had a total of 330 pens left, what was the total number of pens they had at first?
5. Anne has some $2 notes. Cindy has some $5 notes. The ratio of the number of notes Anne has to the number of notes Cindy has is 7 : 5. If Anne gives Cindy 24 notes, the ratio of the number of Anne’s notes to the number of Cindy’s notes will become 1 : 3.
(a) How many $5 notes does Cindy have at first?
(b) Find the total value of all the notes which Anne and Cindy have.
6. A rectangular tank, 56 cm long, 42cm wide and 35 cm high was 3/5 full of water. Water began to leak at a rate of 23 cm3 per second. At the same time, water was also added into the tank from a tap at the rate of 72 cm3 per second. How long would it take for the tank to become 90% full of water?
Give your answer in minutes.)