If a and b are positive numbers, is a

Question

If a and b are positive numbers, is a < c?

(1) The ratio of a to b is 4:1, and the ratio of b to c is 2:7.

(2) ab > bc

TaN1213 · Answer

IMO D
A:B:C 
8:2:7
a>c sufficient

ab>bc
b(a-c) > 0
b is positive so, a-c is positive.
a>c sufficient

Bunuel · Answer

Yes. (1) reads: The ratio of a to b is 4:1, and  the ratio of b to c is 2:7.

Luckisnoexcuse · Answer

(1) a:b:c :: 8:2:7..sufficient

2) ab >bc 
a>c (since b is positive)
sufficient

D

Kimberly77 · Answer

Thanks  Luckisnoexcuse  for explanation. Not quite sure how did you get a=8?

If a and b are positive numbers, is a < c?