The surface of the Grand Lake is at an elevation of 648 feet. During the current drought, the water level is dropping at a rate of 3 inches per day. If this trend continues, write an equation that gives the elevation in feet of the surface of Grand Lake after x days.

I am confused.

I came up with y=3x + 648

Is this right?

new height = original elevation - ((drop per day/12) * number of days)

(we divide by 12 to get the result in feet)

new height = 648 feet - ((3 inches per day/12) * number of days)

y = (-1/4)x + 648

did you get it?

Yes I got it now. Thanks so much for the help.

Well, you're on the right track, but your equation is a little off. Remember, we need to convert the rate of 3 inches per day to feet.

Since there are 12 inches in a foot, we can say that the rate of the water level dropping is 3/12 feet per day, which simplifies to 1/4 foot per day.

So, the correct equation would be:

Elevation = 648 - (1/4)x

Where x is the number of days, and the 1/4 represents the rate at which the water level is dropping. Keep up the good work!

Yes, you are on the right track. To find the elevation of the surface of Grand Lake after a certain number of days, you need to determine the change in elevation with respect to time.

In this case, the water level is dropping at a rate of 3 inches per day. Since there are 12 inches in a foot, we can convert this rate to feet by dividing 3 inches by 12. This gives us a rate of 0.25 feet per day.

To find the elevation after x days, you can multiply the rate (-0.25 feet per day in this case) by the number of days (x). However, since the water level is decreasing, you need to subtract this from the initial elevation.

Therefore, the equation that represents the elevation of the Grand Lake surface after x days can be written as:
elevation (y) = initial elevation (648 feet) + (rate of change (-0.25 feet per day) * number of days (x))

In equation form, this can be simplified as:
y = -0.25x + 648

So, your equation y = 3x + 648 is not correct in this case. The correct equation is y = -0.25x + 648.