If y varies directly with x and y = 3 when x = 12, then what is the value of y when x = 40?
4
160
10
480
3 = 12/4
y=x/4, so ...
y=4?
huh? Huh???
y = x/4
when x=40, y = 40/4
Stop guessing and start calculating...
To determine the value of y when x = 40, we need to use the direct variation relationship between y and x.
When two variables y and x vary directly, it means that they have a constant ratio. This can be represented by the equation y = kx, where k is the constant of variation.
To find the value of k, we can use the given information that y = 3 when x = 12. Plugging these values into the equation, we get 3 = k * 12.
To find the value of k, we divide both sides of the equation by 12:
3/12 = k
k = 1/4
Now that we have the value of k, we can use it to find the value of y when x = 40.
y = k * x
y = (1/4) * 40
y = 10
Therefore, the value of y when x = 40 is 10.