The 4th proportional of 4, 8, 7, ? is _____.
14
14 is correct.
The fourth proportional x of three numbers a, b and c is the number that makes \(a : b = c : x\), so \(x = \dfrac{b \times c}{a}\).
Here \(4 : 8 = 7 : x\), so \(x = \dfrac{8 \times 7}{4} = \dfrac{56}{4} = 14\).
Check: \(4 : 8 = 1 : 2\) and \(7 : 14 = 1 : 2\), so both ratios are equal and the fourth proportional is 14.
Similar Questions
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Important Questions from Fourth Proportional
Find the fourth proportional of (x4 - y4), (x + y) and (x − y), provided x ≠ y.
What is the fourth proportional to the numbers 8, 66 and 112?
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The fourth proportional to 10, 12, 15 is :
Find the fourth proportion of the following numbers.
\(\frac{1}{3}\) of 18, \(\frac{4}{5}\) of 20, \(\frac{3}{7}\) of 28.
