VARIATIONS

The cost c varies directly as the number n of pencils is written as

• c = kn

• k = cn

• n = k/c

• c = k/n

Which is an example of a direct variation?

• xy = 10

• y = 2/x

• y = 5x

• 2/y = x

y varies directly as x and y = 32 when x = 4. Find the constant of variation.

• 8

• 36

• 28

• 128

The speed r of a moving object is inversely proportional to the time t travelled is written as

• r = kt

• r = k/t

• t = kr

• r/k = r

If y varies directly as x and y = 12 when x = 4, find y when x = 12

• 3

• 4

• 36

• 48

A car travels a distance of d km in t hours. The formula that relates d to t is d = kt. What kind of variation is it?

• Direct

• Inverse

• Joint

• Combined

What happens to T when h is doubled in the equation T = 4h?

• T is halved

• T is tripled

• T is doubled

• T becomes zero

If y varies inversely as x, and y = 1/5 when x = 9, find y when x = -3.

• 5

• 1/3

• 3/5

• -3/5

If 3 men can do a portion of a job in 8 days, how many men can do the same job in 6 days?

• 7

• 6

• 5

• 4

In a direct variation a variable k is a

(a)