Originally Posted by

**ridley1013** I'm having some difficulty with the following question:

The following data shows expenditures (in millions of dollars) and case (sales in millions) for 7 major soft drink brands. Calculate the correlation coefficient. Is this significant at the 5% level (ie, α=.05)? Construct the regression equation for this data. Decide how much RC Cola would make if they spend 643.8. Do the same for Canada Dry if they spend 13.8. Is it a good idea to use this regression equation for RC and Canada Dry? Why?

**Brand Spending Sales**

**Coke 131.3 1929.2**

**Pepsi 92.4 1384.6**

**Diet Coke 60.4 811.4**

**Sprite 55.7 541.5**

**Dr Pepper 40.2 536.9**

**Mt Dew 29.0 535.6**

**7-Up 11.6 219.5**

**I made my table & came up with:**

**Ex=420.6**

**Ey=5958.7**

**Exy=500073.09**

**Exsq=35119.7**

**Eysq=7213830.96**

**However, when I used the r formula by hand & by calculator, I came up with 2 different answers: -275.4830985 (hand) & 0.9721001417 (TI-84 calculator). If the calculator is right, how do I get to that answer?**

**Also, any other help anyone can give me with the rest of the problem would be appreciated!**

**Thanks!**