Thread: scatter plots and predictions?

table shows sales of 8 sales men during given time period:

amt sales-yrs of experience
$9000----6
$6000----5
$4000----3
$3000----1
$3000----4
$5000----3
$8000----6
$2000----2

qestions-
1. draw scatter plot-(should this be straight line)?
2. write prediction equation
3. predict sales for 8 yrs of experience
4. predict yrs of experience for selling 7300

b = ?x[i]-xbar)*(y[i]-ybar) / sqrt[?(x[i]-xbar)^2 ?(x[i]-xbar)^2]
regression coefficient is 1191.4894
a = ybar - b*xbar
Constant a is 531.9149
2)Prediction equation: y = 531.9149+1191.4894x
y - sales x = years of experience
3)when x=8, y=sales = 531.9149+1191.4894(8)=10063.8301
You can write sales with 2 decimal digits as they are dollar amounts.
4)Predict x when y=7300
7300 = 531.9149+1191.4894x
solve for x =5.68 years (5 years 8 months)

--------years-------sales------------predicted sales
6.0000 9000.0000 7680.8511
5.0000 6000.0000 6489.3617
3.0000 4000.0000 4106.3830
1.0000 3000.0000 1723.4043
4.0000 3000.0000 5297.8723
3.0000 5000.0000 4106.3830
6.0000 8000.0000 7680.8511
2.0000 2000.0000 2914.8936