標題:
Maths
發問:
1.The sum of three numbers A,B and C is 405. Ais four times of B, and C is greater than A by 45. Find these three numbers.2.In a school 330 students are boys, and they are 60% of the students .Find the total numberof student in the school.3.The share price of a company is now $98.5. If the price increase by 12%... 顯示更多 1.The sum of three numbers A,B and C is 405. Ais four times of B, and C is greater than A by 45. Find these three numbers. 2.In a school 330 students are boys, and they are 60% of the students .Find the total numberof student in the school. 3.The share price of a company is now $98.5. If the price increase by 12% every year,how many years later will the share price be over $300?
1.LET B BE X A=4X C=4X+45 A+B+C=405 4X+X+4X+45=405 9X+45=405 X=40 A=4X =4*40 =160 B=X=40 C=4X+45 =4*40+45 =205 2.330/60%=550
其他解答:
這個「最佳回答」是發問者自選的， 但是， 第一，這個「最佳回答」只在發問者的三條問題當中，答了兩條......而其他答者，則全部答哂！ 第二，這個「最佳回答」是比其餘兩個答者答問題的時間遲六粒鐘...... 第三，這個「最佳回答」答到一舊舊咁，其餘兩個回答則清楚多了！ 這個「最佳回答」不但比其餘兩個回答答得較為遜色， 而且，好話唔好聽，如果這條問題交付投票，都不知有沒有人會選佢......|||||A + B + C = 405 __________(1) A = 4B _________________(2) C - A = 45 ______________(3) From (3), we have: C = 45 + A Sub (3) into (1) , we have: A + B +C = 405 A + B + 45 + A = 405 2A + B = 360 Sub ( 2) into 2A + B = 360, we have: 2 ( 4B ) + B = 360 9B = 360 B = 40 Sub B = 40 into (1), we have: A = 4 ( 40 ) A = 160 Sub A = 160 into ( 3 ) C - 160 = 45 C = 205 So, A = 160, B = 40, C = 205 2) Let the total number of student be n 330 = n * ( 60 / 100) n = 550 So there are 550 students in the school in total. 3) 98.5 * (112/100 ) ^ n > 300 (112/100 ) ^ n > 3000 / 985 (112/100 ) ^ n > 600 / 197 So 10 years later the share price will be over $300 2007-06-11 16:26:53 補充： 三題答得兩題， 仲要是最遲答的那個......|||||1. A + B + C = 405 A = 4B B = A/4 C = A + 45 Solve A: 405 = A + A/4 + A+ 45 360 = 2A + 1/4 A 360 = 2.25A A = 360/2.25 A = 160 B = A/4 B = 160/4 B = 40 C = A + 45 C = 160 + 45 C = 205 160 + 40 + 205 = 405 2. X = Total number of student in the school 0.6 X = 330 X = 330/0.6 X = 550 3. This is a compound interest question: F = P (1 + r)^t F = future value P = Initial deposit r = rate of increase per year t = number of years You are given: F = 300, P = 98.5, r = 12%, solve t 300 < 98.5 (1 + 0.12)^t 300/98.5 < 1.12^t 1.12^t > 3.05 t = 10
Maths
發問:
1.The sum of three numbers A,B and C is 405. Ais four times of B, and C is greater than A by 45. Find these three numbers.2.In a school 330 students are boys, and they are 60% of the students .Find the total numberof student in the school.3.The share price of a company is now $98.5. If the price increase by 12%... 顯示更多 1.The sum of three numbers A,B and C is 405. Ais four times of B, and C is greater than A by 45. Find these three numbers. 2.In a school 330 students are boys, and they are 60% of the students .Find the total numberof student in the school. 3.The share price of a company is now $98.5. If the price increase by 12% every year,how many years later will the share price be over $300?
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最佳解答:1.LET B BE X A=4X C=4X+45 A+B+C=405 4X+X+4X+45=405 9X+45=405 X=40 A=4X =4*40 =160 B=X=40 C=4X+45 =4*40+45 =205 2.330/60%=550
其他解答:
這個「最佳回答」是發問者自選的， 但是， 第一，這個「最佳回答」只在發問者的三條問題當中，答了兩條......而其他答者，則全部答哂！ 第二，這個「最佳回答」是比其餘兩個答者答問題的時間遲六粒鐘...... 第三，這個「最佳回答」答到一舊舊咁，其餘兩個回答則清楚多了！ 這個「最佳回答」不但比其餘兩個回答答得較為遜色， 而且，好話唔好聽，如果這條問題交付投票，都不知有沒有人會選佢......|||||A + B + C = 405 __________(1) A = 4B _________________(2) C - A = 45 ______________(3) From (3), we have: C = 45 + A Sub (3) into (1) , we have: A + B +C = 405 A + B + 45 + A = 405 2A + B = 360 Sub ( 2) into 2A + B = 360, we have: 2 ( 4B ) + B = 360 9B = 360 B = 40 Sub B = 40 into (1), we have: A = 4 ( 40 ) A = 160 Sub A = 160 into ( 3 ) C - 160 = 45 C = 205 So, A = 160, B = 40, C = 205 2) Let the total number of student be n 330 = n * ( 60 / 100) n = 550 So there are 550 students in the school in total. 3) 98.5 * (112/100 ) ^ n > 300 (112/100 ) ^ n > 3000 / 985 (112/100 ) ^ n > 600 / 197 So 10 years later the share price will be over $300 2007-06-11 16:26:53 補充： 三題答得兩題， 仲要是最遲答的那個......|||||1. A + B + C = 405 A = 4B B = A/4 C = A + 45 Solve A: 405 = A + A/4 + A+ 45 360 = 2A + 1/4 A 360 = 2.25A A = 360/2.25 A = 160 B = A/4 B = 160/4 B = 40 C = A + 45 C = 160 + 45 C = 205 160 + 40 + 205 = 405 2. X = Total number of student in the school 0.6 X = 330 X = 330/0.6 X = 550 3. This is a compound interest question: F = P (1 + r)^t F = future value P = Initial deposit r = rate of increase per year t = number of years You are given: F = 300, P = 98.5, r = 12%, solve t 300 < 98.5 (1 + 0.12)^t 300/98.5 < 1.12^t 1.12^t > 3.05 t = 10
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