If X:Y is 1:5 and Y:Z is 5:7 then X:Z is equal to	Choose the correct choice from the following options.
A) 1 : 6
B) 1 : 5
C) 1 : 4
D) 1 : 7
E) 1 : 3

Rationale: the two ratios given are having the same number 5 for y in both the ratios . hence - x : y = 1 : 5 y : z = 5 : 7 = > x : z = 1 : 7 answer d
Answer: D