Direct & Inverse Variation

Y is directly proportional to the square of z and inversely proportional to w.

• y=kz²/w

• y=kz/w

• y=w/kz²

• y=w/kz

The interest received on a savings account varies directly with the amount deposited. Daniel received $55.35 in interest on $1230 he deposited. How much interest would Daniel have received if he had deposited $2000 into his account?

• 34.04

• 90.00

• 1,285.35

• 44,444.44

y varies directly with the square of x.  If y=40 when x=4, find y when x = 7

• 17.5

• 70

• 122.5

a varies inversely as the square of b. If a is 1 when b is 3, find a when b is 5. 

• 0.36

• 9

• 25

• 36

The Height of a wave in California varies directly with the seconds that pass by.  At 4 seconds, the wave is 6 feet high.  How many seconds will give you a wave that is 10 feet high? 

• y = 2/3x

• 6

• 6.6

• 7

The width of a rectangle varies inversely with its length. if the width is 4 when the length is 18, find the width when the length is 8.

• 9

• 72

• 36

• 2

y varies directly as x, if y=12 when x=5, find y when x=3

• 36/5

• 15/12

• 12/5

• 12/15

y varies directly as x, if y=4 when x=3, find x when y=-12

• -16

• 16

• -9

• 9

Points (3,10) and (x, 15) represent a direct variation. Find x.

• 50

• 5

• 3.5

• 4.5

y varies inversely as x, if y = -3 when x = -6, find y when x = 14.

• 11

• -11

• 9/7

• 7/9