Four questions of Ratio part A (10 marks)－yanahv7的部落格

標題:

Four questions of Ratio part A (10 marks)

發問:

1) A sum of $72 is divided among A,B and C. The amount that A gets is 1/2 of B and 1/3 of C. How much does each of them get ? 2) A is twice as old as B and B is half as old as C. If the sum of thier ages is 65 years, how old is A ?

最佳解答:

1) A sum of $72 is divided among A,B and C. The amount that A gets is 1/2 of B and 1/3 of C. How much does each of them get ? Let A get $x, B get $2x, C get $3x x + 2x + 3x = 72 6x = 72 x = 12 // A gets $12, B gets $24, C gets $36 2) A is twice as old as B and B is half as old as C. If the sum of thier ages is 65 years, how old is A ? Let A be x years old, B be x/2 years old, C be x years old x + x + (x / 2) = 65 2x + (x / 2) = 65 4x + x = 130 5x = 130 x = 26 // A is 26 years old, B is 13 years old, C is 26 years old

其他解答:

1) A sum of $72 is divided among A,B and C. The amount that A gets is 1/2 of B and 1/3 of C. How much does each of them get? The ratio of the money they get is: A B C 1/2 1 (X 1/3) 1/3 1 (X 1/2) _________ 1/6 1/3 1/2 (X6) 1 2 3 $72/(1+2+3)=$72/6=$12 Thus, a proportion is $12 So A gets $12, B gets $24, C gets $36. A B C 2 1 1 2 _________ as 1 in B is repeated, a direct (2 1 2) 2 1 2 as 1 in B is repeated, a direct (2 1 2) is also accepted. 65/(2+1+2)=65/5=13 Thus, a proportion is 13 years old. So A is 26 years old, B is 13 years old, C is 26 years old.