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In a proportion a : b :: c : d, the product of means (b ├Ч c) equals the product of extremes (a ├Ч d). Here, x ├Ч y = 6 ├Ч 6 = 36.
Given ratio x : 6 :: 6 : y
x:6::6:yтЯ╣6xтАЛ=y6тАЛтЯ╣xy=36
In a proportion a : b :: c : d, the product of means (b ├Ч c) equals the product of extremes (a ├Ч d). Here, x ├Ч y = 6 ├Ч 6 = 36.
Students often try to find the individual values of x and y, which is impossible without another equation; however, the product xy is fixed.
Set up the proportion
The given proportion is x:6::6:y. This means the ratio of x to 6 is equal to the ratio of 6 to y.
6xтАЛ=y6тАЛ
Calculate the product xy
Cross-multiply to isolate the product of the terms: x├Чy=6├Ч6.
xy=36
Find the square root
The question asks for the value of xyтАЛ. Substituting xy=36, we get 36тАЛ=6.
xyтАЛ=36тАЛ=6
A is correct because the property of proportion dictates that x├Чy=6├Ч6=36, so xyтАЛ=36тАЛ=6.
This concept of mean proportional is fundamental in geometry, specifically when calculating the altitude of a right-angled triangle relative to the segments of the hypotenuse.