The ratio of the third proportion of 5 and 12 with the fourth proportion of 5, 8, and 9 is:
Show answer & explanation
Correct answer: A
Explanation
The correct answer is Option 1 i.e. 2 : 1.
Let the given numbers be a and b and, the third proportional be x
Then, a/b = b/x
x = b2/a
Similarly, in the given question
x = 144/5
Let the given numbers be a, b, and c, and, the fourth proportional be x
Then, a/b = c/x
x = bc/a
Similarly, in the given question
⇒ a = 5, b = 8, and c = 9
⇒ x = (8 × 9)/5
⇒ x = 72/5
Hence, the fourth proportion is 72/5
Required ratio = 144/5 : 72/5 = 2 : 1