Correct Answer - Option 1 : 12
Given:
x is subtracted from each of the numbers 20, 37, 54 and 105, then the numbers so obtained in this order are in proportion.
Concept used:
Ratio and proportion
Calculation:
x is subtracted from each of the numbers 20, 37, 54 and 105,
⇒ \(\frac{{20\ - x}}{{37\ - x}} = \frac{{54\ - x}}{{105\ - x}}\)
⇒ 2100 - 125x = 1998 - 91x
⇒ 102 = 34x
⇒ x = 3
Mean proportion = \(\sqrt {xy} \)
Mean proportion between (7x - 5) and (x + 6)
⇒ \(\sqrt {\left( {7x - 5} \right)\left( {x + 6} \right)} \)
⇒ \(\sqrt {16 \times 9} \)
⇒ √144
∴ Ans = 12
