Aptitude - Ratio and Proportion - Discussion

Discussion Forum : Ratio and Proportion - General Questions (Q.No. 13)
13.
The fourth proportional to 5, 8, 15 is:
18
24
19
20
Answer: Option
Explanation:

Let the fourth proportional to 5, 8, 15 be x.

Then, 5 : 8 : 15 : x

5x = (8 x 15)

x = (8 x 15) = 24.
5

Discussion:
34 comments Page 4 of 4.

Ramya Reddy said:   2 years ago
5*3 = 15
8*3 = 24 that's the answer.
(13)

Pranav said:   1 year ago
Here is the solution

Let's write 5, 8, 15, X.
= (5/8) : (15/x),
= 15/x * 8/5,
Then x.= 3*8.
So, the Answer = 24.
(5)

Sumit Singh said:   1 year ago
The formula for finding the fourth proportional = b*c/a.
A = 5, B = 8, C = 15,
8*15/5 = 24.
(4)

Akash said:   4 months ago
Formula:
x = b * c/a.
Then substitue the given values;
8 * 15/5 = 120/5.
x = 24.
(3)


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