If y varies directly as x and y = 34 when x = 7, find y when x = 49.

A. 7
Incorrect. Find k using the points (0,0) and (7,34). Substitute 49 for x, and use the value k in the equation y = kx.

B. 5
Incorrect. Find k using the points (0,0) and (7,34). Substitute 49 for x, and use the value k in the equation y = kx.

C. 238
Correct! The slope, or k, equals 34 divided by 7. Substitute 49 for x into y = 34/7(x), y = 238 hours.

D. 1666
Incorrect. Find k using the points (0,0) and (7,34). Substitute 49 for x, and use the value k in the equation y = kx.

Canadian Snow Geese migrate to the Canadian arctic in the summer. One flock migrated 500 kilometers in 6 hours. Find the number of hours it would take them to travel 4,500 kilometers.

A. 9 hours
Incorrect. Find k using the points (0,0) and (6,500). Substitute 4500 kilometers in for y, and use the value of  k in the equation y = kx.

B. 3000 Hours
Incorrect. Find k using the points (0,0) and (6,500). Substitute 4500 kilometers in for y, and use the value of  k in the equation y = kx.

C. 6 Hours
Incorrect. Find k using the points (0,0) and (6,500). Substitute 4500 kilometers in for y, and use the value of k in the equation y = kx.

D. 54 Hours
Correct! The slope, or k, equals 500 divided by 6 or 250 over 3. Substitute 4,500 kilometers for y into y = 250/3(x), x = 54 hours.

The table below represents the number of chair legs in a room. If there are 230 chairs in the room, find the number of chair legs.

A. 16
Incorrect. Find k using the points (1,4) and (2,8). Substitute 230 for y and use the value of k in the equation y = kx.

B. 920
Correct! The slope, or k, equals 4. Substitute 230 in for x into y = 4(x), y = 920.

C. 1840
Incorrect. Find k using the points (1,4) and (2,8). Substitute 230 for y and use the value of k in the equation y = kx.

D. 58
Incorrect. Find k using the points (1,4) and (2,8). Substitute 230 for y and use the value of k in the equation y = kx.

Which of the following graphs best represents a direct variation relationship?

A.

Correct!

B.

Incorrect. The graph of a direct variation relationship passes through the origin, but is also linear. This graph does not show a linear relationship.

C.

Incorrect. This graph represents a constant function, which is not a direct variation.

D.

Incorrect. This graph shows a linear function, but does not pass through the origin.

A direct variation is graphed below. Find the value of y when x is 24.

A. 24
Incorrect. Use the graph; find the point on the line where the x value is 24. Find the corresponding y value.

B. 12
Correct! Using the graph, find where x is equal to 24. The corresponding y value is 12.

C. 10
Incorrect. Use the graph; find the point on the line where the x value is 24. Find the corresponding y value.

D. 16
Incorrect. Use the graph; find the point on the line where the x value is 24. Find the corresponding y value.