Linear Function E(t) HELP!

[pearldrops]

In 1991, the life expectancy of males was 64.2 years. In 1998, it was 67.1 years. Let E represent the life expectancy in year t and let t represent the number of years since 1991.

Function that fits the data is :
E(t)=___t + ___ Round to the nearest tenth

Use function to predict the life expectancy in 2009.

E(18)= ____

I have looked at it working like this: E(t)= 64.2t + 7
I do not know if this is going to work out or if I am doing it correctly but then for the second part I am figuring the 64.2 times 18.
Can anyone help! Please show me how to work these so I can figure out how to do it on my own.

 

[mmm4444bot]

Have you written any equations for lines before ? The graph of a linear function is a line.

In 1991, t = 0, and E = 64.2

In 1998, t = 7 and E = 67.1

Those are coordinates for two points on the xy-plane, only the axes have changed names. Instead of (x,y) coordinates, we have (t,E) coordinates.

In other words, the x-axis is now called the t-axis, and the y-axis is now called the E-axis.

The linear function's graph is a line through these two points: (0, 64.2) and (7, 67.1)

Have you learned the formula for slope ? This exercise asks you for the slope. It also asks for the y-intercept (or, in this case, the E-intercept).

After you fill in those two blanks, you'll have the function definition for function E. Use it to find E(18)

If you haven't learned about slope-intercept forms for equations of lines, you'll need to complete some lessons.

Otherwise, please show us what you've done so far.