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F.1 maths
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1 , In a school , 55% of the student are boys . If there are 484 boys , find the total number of students in the school . 2 , The total volume of material of a bottle and the mixture of water and alcohol inside is 2500 cm3.15% is the volume of the material and 68% of the mixture is alcohol . Find the volume of... 示更多 1 , In a school , 55% of the student are boys . If there are 484 boys , find the total number of students in the school . 2 , The total volume of material of a bottle and the mixture of water and alcohol inside is 2500 cm3.15% is the volume of the material and 68% of the mixture is alcohol . Find the volume of water.
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1 Let y be the number of students in the school y x 55% = 484 y x 0.55 除 0.55 = 484 除 0.55 y = 880 So,there are 880 students in the school 2. The first method Let x be the volume of water x ( 2500 x 15%) ( 2500 x 68 %) = 2500 x 加 375 加 1700 = 2500 x = 2500 - 375 -1700 x = 425 Second method 2500 x ( 1 - 15% 68% ) = 2500 x 17% = 2500 x 0.17 = 425 So,the volume of water is 425 cm^3
其他解答:
1. 484/55% = 484x100/55 = 880 students 2. 2500x(1-15%-68%) = 2500x17% = 2500x17/100 = 425cm3|||||1. 484/55% =484/ 55/100 =484*100/55 =44*20/1 =880(people) 2. 2500/(1-15%-68%) =2500/(85%-68%) =2500/17% =2500/ 17/100 =2500*100/17 =250000/17 =14705 15/17(cm^3) 2008-06-09 12:05:25 充： sorry, no.2 is wrong, it should be 2500*(1-15%-68%) =2500*(85%-68%) =2500*17% =2500*17/100 =25*17 =425(cm^3)CF546184A985CA23
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