Math 9 2nd Quarter Exam

Which is an example of a direct linear variation?

• xy = 5

• y = 3/x

• y = 2x

• 3/y = x

An encoder can type n words in t hours. The formula that relates n to t is n = k/t. What kind of variation is it?

• inverse

• direct

• joint

• combined

If p varies directly as q and inversely as r, then which of the following equations describes the relation among the variables?

• p = kq/r

• 1/p = kr/q

• p = kr/q

• p = k/qr

Translate into equation, “y is directly proportional to x and inversely proportional to z“. Use k as constant of proportionality.

• y = kxz

• y = kz/y

• y = kx/z

• y = x/ky

Derive the equation for the variation using the table below.

• y = 3x

• y = -3/x

• y = -3x

• xy = 3

If v varies directly as the square of x and inversely as y and z. If v = 12 when x = 4, y = 2 and z = 2. Find v when x = 3, y = 8 and z = 5.

• A. 10

• B. 9

• C. 27/4

• D. 5

• S is halved

• S is doubled

• S is quadrupled

• S is multiplied by 6

What happens to T when h is tripled in the equation T = k/h?

• T is tripled

• T is multiplied by 6

• T is divided by 6

• T is divided by 3

Mike’s income varies directly as the number of days that he works. If his number of days tripled, what happens to his income?

• divided by 3

• multiplied by 9

• tripled

• quadrupled

The area of a circle is proportional to the square of its radius. If the length of its radius is halved, what happens to its area?

• doubled

• divided by four

• multiplied by four

• quadrupled