Write and solve a direct variation equation to find the length of the spring when a 63 pound weight is attached.

Question

When a 49 pound weight is attached to a spring, the spring stretches 7 inches. Assume that the length of the spring y varies directly with the weight attached x.

Answer 1

ANSWER: 9 inches

 

If two values directly vary, then we know that their quotients will always be the same

 

So in this example, the weight/distance stretched will always equal 49/7=7

 

So if the weight is 63 pounds we know that 63 divided by the distance stretched must also equal 7. Set up the following equation and solve for x:

 

63/x=7

x=63/7

x=9 inches