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maths (quickly)
發問:
1) 1/2 : 7=5 : a = 2b : 56find the two unknown2)the population of a town was 5 000 000 which included 875000 newborn babies. What was the birth rate in births per 1 00 people?3)the temperature of water in an electric boiler is raised from 25℃to 100℃ in 15 minutes. what is the rate of temperature rise in... 顯示更多 1) 1/2 : 7=5 : a = 2b : 56 find the two unknown 2)the population of a town was 5 000 000 which included 875000 newborn babies. What was the birth rate in births per 1 00 people? 3)the temperature of water in an electric boiler is raised from 25℃to 100℃ in 15 minutes. what is the rate of temperature rise in ℃per mimute? 更新: need to step!!! 更新 2: re : 1) What was the birth rate in births per 1 000 people?
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其他解答:
1) 1/2 : 7=5 : a = 2b : 56 1/2 : 7=5 : a 0.5:7=5:a 0.5a=7(5) a=7(5)/0.5 a=70 5 : a = 2b : 56 5:70=2b:56 70(2b)=56(5) 140b=56(5) b=56(5)/140 b=2 2)newborn babies/100=875000/5000000 875000/5000000*100=1.75 The rate is100:1.75. ====== 3)25/15= 2 1--- 3|||||1) 1/2:7=5 : a = 2b : 56 (1/2)/7=5/a=2b/56 so (1/2)/7=5/a a/14=5 a=70 so 2b/56=5 b=140 2)唔係太明(the birth rate in births per 1 00 people) 3) (100℃-25℃)/15 =5℃/mins|||||1) 1/2 : 7=5 : a = 2b : 56 0.5:7=5:a 5:70=5:a -----------(0.5 x 10:7 x 10) a=70 0.5:7=2b:56 -----------(0.5 x 8:7 x 8) 4:56=2b:56 b=4 2) 875000/5000000 x 100 = 17.5 per 100 people 3) (100-25)/15 =75/15 =5℃per mimute
maths (quickly)
發問:
1) 1/2 : 7=5 : a = 2b : 56find the two unknown2)the population of a town was 5 000 000 which included 875000 newborn babies. What was the birth rate in births per 1 00 people?3)the temperature of water in an electric boiler is raised from 25℃to 100℃ in 15 minutes. what is the rate of temperature rise in... 顯示更多 1) 1/2 : 7=5 : a = 2b : 56 find the two unknown 2)the population of a town was 5 000 000 which included 875000 newborn babies. What was the birth rate in births per 1 00 people? 3)the temperature of water in an electric boiler is raised from 25℃to 100℃ in 15 minutes. what is the rate of temperature rise in ℃per mimute? 更新: need to step!!! 更新 2: re : 1) What was the birth rate in births per 1 000 people?
最佳解答:
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1) 1/2 : 7=5 : a 0.5 ÷ 7 = 5 ÷ a a = 7×5÷.5 a = 70 1/2 : 7 = 2b : 56 0.5÷7 = b÷28 b= 2 2) birth rate =875000÷5 000 000×100 =875÷5 0 =17.5 per 1 00 people 3) rate of temperature rise =(100-25)÷15 =5℃per mimute其他解答:
1) 1/2 : 7=5 : a = 2b : 56 1/2 : 7=5 : a 0.5:7=5:a 0.5a=7(5) a=7(5)/0.5 a=70 5 : a = 2b : 56 5:70=2b:56 70(2b)=56(5) 140b=56(5) b=56(5)/140 b=2 2)newborn babies/100=875000/5000000 875000/5000000*100=1.75 The rate is100:1.75. ====== 3)25/15= 2 1--- 3|||||1) 1/2:7=5 : a = 2b : 56 (1/2)/7=5/a=2b/56 so (1/2)/7=5/a a/14=5 a=70 so 2b/56=5 b=140 2)唔係太明(the birth rate in births per 1 00 people) 3) (100℃-25℃)/15 =5℃/mins|||||1) 1/2 : 7=5 : a = 2b : 56 0.5:7=5:a 5:70=5:a -----------(0.5 x 10:7 x 10) a=70 0.5:7=2b:56 -----------(0.5 x 8:7 x 8) 4:56=2b:56 b=4 2) 875000/5000000 x 100 = 17.5 per 100 people 3) (100-25)/15 =75/15 =5℃per mimute
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