✔ 最佳答案
1/a : 1/b = 2 : 3
2 * (1/b) = 3 * (1/a)
2/b = 3/a
b/2 = a/3
b = (2/3)a
a : c = 4 : 1
c * 4 = a * 1
c = (1/4)a
Hence, a : b : c
= a : (2/3)a : (1/4)a
= 12*a : 12*(2/3)a : 12*(1/4)a
= 12 : 8 : 3
2011-08-19 02:24:04 補充:
Alternative method :
1/a : 1/b = 2 : 3
a : b = (1/2) : (1/3)
a : b = 24*(1/2) : 24*(1/3)
a : b = 12 : 8
a : c = 4 : 1
a : c = 12 : 3
a : b = 12 : 8 and a : c = 12 : 3
Hence, a : b : c = 12 : 8 : 3 ...... (answer)