我星期六就要補數,但校內測緊驗,冇時間做,有兩條唔識~
來自New Progress in Junor Mathematics Workbook 2A
Chapter1 Ratio and Rate
10) Kevin mixed 6L of alcohol with 4L of water and Jerry mixed 3L of alcohol with 5L of water.
a) How much water should Kevin further add to his mixture so that there is 50% of alcohol?
b) They now mix their mixtures together. How much alcohol should they add to their mixture so that there is 75% of alcohol?
11) Alvin has 2 model cars A and B. Car A's speed is 2m/s and car B's speed is 3m/s. He puts the cars on the same track to travel 100m.
a) Find the difference between the times needed for car A and car B to travel 100 m.
b) Alvin increases car A's speed by 100%.Find the percentage increase in the speed of car B so that it finishes the track ahead of car A by 5 seconds.
各位除了提供答案,式& steps 外,最好解一解,THX~~