Q1 of 7 Page 68

In each example, find the constant of proportionality and write the equation of variation.

(1) When y = 15, x = 14


(2) When w = 24, z = 2.5


(3) When t = 5.5, s = 4.4

(1) y ∝ ⇒ y = k × ⇒ xy = k(constant of proportionality)


When y = 15, x = 14


⇒ k = xy = 15 × 14


∴ k = 210


Constant of proportionality = 210


Equation of variation is xy = 210


(2) z ∝ ⇒ z = k × ⇒ zw = k(constant of proportionality)


When z = 2.5, w = 24


⇒ k = zw = 2.5 × 24


∴ k = 60


Constant of proportionality = 60


Equation of variation is zw = 60


(3) s ∝ ⇒ s = k × ⇒ st = k(constant of proportionality)


When s = 4.4, t = 5.5


⇒ k = st = 4.4 × 5.5


∴ k = 24.2


Constant of proportionality = 24.2


Equation of variation is st = 24.2


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