Aptitude - Ratio and Proportion - Discussion
Discussion Forum : Ratio and Proportion - General Questions (Q.No. 13)
13.
The fourth proportional to 5, 8, 15 is:
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 3 of 4.
Isaacs nyondo said:
1 decade ago
It is really supposed to be.
5:8 = 15:x.
It means that they are terms of a sequence.
Then:
5/8 =15/x.
x = 15*8/5.
x = 24.
5:8 = 15:x.
It means that they are terms of a sequence.
Then:
5/8 =15/x.
x = 15*8/5.
x = 24.
Sumitra said:
1 decade ago
It should be like this 5:8::15:x.
Then 5/8 = 15/x.
x = 15*8/5.
x = 24.
Then 5/8 = 15/x.
x = 15*8/5.
x = 24.
Shipra said:
1 decade ago
Hello guys!
Its given,
5:8:15:x.
Where we take x as constant.
Now,
5/8 = 15/x.
=> 5 = (15*8)/x.
On cross multiplication we get,
x = (15*8)/5.
x = 3*8.
x = 24.
Its given,
5:8:15:x.
Where we take x as constant.
Now,
5/8 = 15/x.
=> 5 = (15*8)/x.
On cross multiplication we get,
x = (15*8)/5.
x = 3*8.
x = 24.
Samim said:
1 decade ago
5:8 = 15:x.
5/8 = 15/x.
5x = 15*8.
x = 90/5.
x =18.
5/8 = 15/x.
5x = 15*8.
x = 90/5.
x =18.
Hanson said:
1 decade ago
Better still:
It will be split this way: 5:8=> 15:x.
Hence, the common factor is 15/5 = 3.
Thus, x/8 = 3.
x= 8*3 =24.
It will be split this way: 5:8=> 15:x.
Hence, the common factor is 15/5 = 3.
Thus, x/8 = 3.
x= 8*3 =24.
Divya said:
1 decade ago
Let the 4th proportional to 5:8::15:x.
Product of extremes = product of means.
5x = 8*15.
x = 120/5.
= 24.
Product of extremes = product of means.
5x = 8*15.
x = 120/5.
= 24.
Azeem said:
1 decade ago
Assume a=5, b=8, c=15.
We all know the ad = bc.
a = bc/d, b = ad/c, c = ad/b.
Simillarly d = bc/a.
So 8*15/5 => 120/5 = 24.
We all know the ad = bc.
a = bc/d, b = ad/c, c = ad/b.
Simillarly d = bc/a.
So 8*15/5 => 120/5 = 24.
Priyankapatil said:
1 decade ago
How to find fifth proportional?
Reethrose said:
1 decade ago
5:8::15:?
5*3=15
8*3=24
so the answer is 24.
5*3=15
8*3=24
so the answer is 24.
Shrishti said:
1 decade ago
This is solved by proportional formula such as a:b :: c:d
Formula: a*d=b*c (as said find fourth proportional).
Formula: a*d=b*c (as said find fourth proportional).
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