MATHEMATICS

JAMB 2011 - Question 16

Mathematics 2011 JAMB Past Questions - Question 16: if x varies directly as square root of y and x=81 when y=9,find x when y=1 7/9

if x varies directly as square root of y and x=81 when y=9,find x when y=1 7/9
A:
B:
C:
D:
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Correct Answer

D

Explanation

If x varies directly as the square root of y, we can write the equation as x = ky^(1/2), where k is the constant of variation.To find the value of k, we can substitute the given values of x and y into the equation:81 = k * 9^(1/2)Taking the square root of 9, we have:81 = k * 3Solving for k, we divide both sides of the equation by 3:k = 81 / 3k = 27Now that we have the value of k, we can use it to find x when y = 1 7/9:x = 27 * (1 7/9)^(1/2)To simplify (1 7/9)^(1/2), we convert the mixed number to an improper fraction:x = 27 * (16/9)^(1/2)Taking the square root of 16/9, we have:x = 27 * (4/3)Simplifying further:x = 27 * 4/3x = 36Therefore, when y = 1 7/9, x = 36.