Step 1. Open Excel and complete first two columns with any numbers Make 7-8 rows. Type below first column "R = " We will use Excel function CORREL(Array-1, Array-2). STEP 2. Click on cell B11 and type: =CORREL(x-Array, y-Array)  When you highlight x-array and y-array do not include the title. Press ENTER. You will see in cell B11 Coefficient of Linear Correlation. STEP 3. Analyze the R-value. Does it mean we have strong positive, strong negative, weak correlation or none linear correlation.  STEP 4. Find equation of best fit line for your set of numbers. Equation should be in form:  y = Ax + B where A is a slope and B is y-intercept. To find A and B use Excel functions:  A (slope) = SLOPE(y-array, x-array) B (y-intercept) = INTERCEPT(y-array, x-array) STEP 5. Use your equation of best fit line  to calculate y at any point outside your x-interval.