Math 9 Quiz #1

If m varies directly as n, then m=kn.

• True

• False

If m varies directly as b, then m = nb.

• True

• False

If m varies directly as the square root of n, then

 $m=k\sqrt{n}$  

• True

• False

If m is directly proportional to n, the equation must be written as _____________.

• mn = k

•  $k=\frac{m}{n}$  

•  $m=\frac{k}{n}$  

• none of the above

If a and b are dependent and independent variables respectively, which equation shows inverse variation?

• $ab=k$

• $\frac{a}{b}=k$

• $m=\frac{k}{n}$

• none of the above

If

 $x=\frac{k}{y}$  , then __________.

•  $x_1y_1=x_2y_2$  

•  $x_1x_2=y_1y_2$  

•  $x_1y_2=x_2y_1$  

• none of the above

In a direct variation, if the independent variable is doubled, what will happen to the dependent variable?

• The dependent variable is also doubled.

• The dependent variable is increased by 2.

• The dependent variable is divided by 2.

• none of the above

If y is directly proportional to (3x + 2) and y=4 when x=2, find y when x=6.

• 10

• 7

• 12

• 8

The electric current I (in amperes) of an electric circuit varies directly as the voltage V. When 24 volts is applied, the current is 8 amperes. Find the current when 12 volts is applied.

• 4 amperes

• 5 amperes

• 6 amperes

• 7 amperes

The amount (A) that a family gives to charitable institution varies directly as its income (I). Last year, the family earned Php 1 600 000 and gave Php 128 000 to charity. How much will they give if they earned Php 2 100 000 this year?

• Php 168 000

• Php  170 000

• Php 169 000

• Php 166 000