Direct Proportion Applications

Y varies directly as x. If y = 12 when x = 15, what is y when x = 20?

• 4/5

• 17

• 16

• 25

n varies directly with c. If c = 24 when n = 18, what is c when n = 22?

• 88/3

• 28

• 66/4

• 24

Which equation exhibits a direct proportion?

• y = 5x - 2

• y = 3/4 x

• y - x = 4

• x = 6

What is the value of k in the following equation? y = 2/7 x

• 4

• -4

• 2/7

• 7

You can buy 4 tickets for $75 or 5 tickets for $94. Are the costs proportional?

• yes

• no

Two quantities are proportional if :

• numerator x numerator = denominator x denominator

• unit rates are the same

• one quantity is bigger than the other

How do you know whether two quantities x and y are proportional?

• Every sum x + y is the same for related pairs of x and y.

• Every x term is a multiple of the previous term.

• Every difference x – y is the same for related pairs of x and y.

Answer explanation

Proportional relationships are equivalent ratios.

Tags

CCSS.MATH.CONTENT.7.RP.A.2.a

A falcon bird flies 35 meters in 10 seconds.  If it keeps flying at the same rate, how long will it take it to fly 14 more meters?  

Hint: Use your knowledge of proportional reasoning!

• x = 49 seconds

• x = 4 meters

• x = 49 meters

• x =  4 seconds

Determine if the following pairs of quantities are proportional: (2, 3), (4, 6), (6, 9).

• Yes

• No

For an equation to be directly proportional, it must .......

• pass thru two points

• pass thru the origin

• be positive

• not have a fraction