Question

# A department of transportation’s study on driving speed and miles per gallon for midsize automobiles resulted...

A department of transportation’s study on driving speed and miles per gallon for midsize automobiles resulted in the following data:

Speed (Miles per Hour)Miles per Gallon: 30 51 39 55 30 24 61 24 50 56

Miles per Gallon: 29 25 25 23 31 33 20 35 26 24

Compute the sample correlation coefficient (to 2 decimals and enter negative value as negative number).

What can you conclude, based on your computation of the sample correlation coefficient?

 x y x^2 y^2 xy 30 29 900 841 870 51 25 2601 625 1275 39 25 1521 625 975 55 23 3025 529 1265 30 31 900 961 930 24 33 576 1089 792 61 20 3721 400 1220 24 35 576 1225 840 50 26 2500 676 1300 56 24 3136 576 1344 Total 420 271 19456 7547 10811

Correlation coefficient

=-0.94

Therefore, we an conclude that , there is very strong negative correlation between  driving speed and miles per gallon

We can directly calculate correlation coefficient by using Excel.

Step 1)  Enter data in Excel.

Step 2 )  Then use =CORREL command and select two separate column data  >> ok

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