Direct Variation

The fare F of a passenger varies directly as the distance d of his destination.

(a)  

The cost C of fish varies directly as its weight w in kilograms

(a)  

An employee’s salary S varies directly as the number of days d he has worked.

(a)  

The area A of a square varies directly as the square of its side s.

(a)  

The distance D travelled by a car varies directly as its speed s.

(a)  

Suppose y varies directly as x, and y = 16 when x = 8. Find y when x = 16

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• 33

Suppose y varies directly as x, and y = 21 when x = 3. Find x when y = 42.

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Suppose v varies directly as g, and v = 36 when g = 4.

Find v when g = 11.

• 99

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Suppose a varies directly as b, and a = 7 when b = 2.

Find b when a = 21.

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Suppose y varies directly as x, and y = 9 when x = 3/2.

Find y when x = 1.

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