If a :b = 2 : 3, b : c = 5 : 7, then find the ratio c : a.
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 21 : 10.
a : b = 2 : 3 .....(1)
b : c = 5 : 7 .....(2)
Multiplying the first ratio by 5,
a : b = 10 : 15
Multiplying the second ratio by 3,
b : c = 15 : 21
So, a : b : c = 10 : 15 : 21
Then, c : a = 21 : 10
Therefore, the value of c : a is 21 : 10.