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easyMCQCompetitive Exam Practice2026Quantitative Aptitude
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Find the fourth proportional of 3,7,12.

  1. A
    42
  2. B
    28
  3. C
    36
  4. D
    21

Solution & Step-by-step Explanation

Let the fourth proportional of 3,7,12 be x.
By definition of proportionality:

3:7::12:x
7
3
​
=
x
12
​

Cross-multiplying to solve for x:

3×x=7×12
3x=84
x=
3
84
​
=28
Thus, the fourth proportional is 28.

Practice this question

Try it yourself before checking the explanation above.

Find the fourth proportional of 3,7,12.
A
42
B
28
C
36
D
21

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Ratio and Proportion

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