# Semi-Variable Costs: The correlation coefficient Example 3

1. says

I don’t know if I made a mistake somewhere along in the calculation but i’m having a problem… I used to full figures in thousands for costs and hundreds for units. So, for I have Sum(X) = 2800, Sum(Y) = 420,000, Sum(XY) = 187,000,000, Sum(X^2) = 1,400,000 and Sum(Y^2) = 26,550,000. When I plugged these values into the equation, (the numerator): Square root of [(7*1,400,000)-(2800^2)] X [(7*26,550,000)-(420,000^2)]. My problem is with the values in the last bracket. 420,000^2 is more than (7×26,550,000) which means under the square root I’m getting a negative value. Please Help

2. says

For Example 2. the ending for b was 6.7857, but when converted to units is was not 67.86. If the units were in hundreds, why is the answer not 678.57

• says

The costs are in 1000’s which gives 6785.7 for b, but the units are in 100’s, which makes b 6785.7/100 = 67.857

• Pls sir, could you explain this in another form as I didn’t get how u applied 1000s and 100s

3. says

thank you for all the lessons! Wishing you – the lecturer and organiser team all the best!

• says

If you mean question 1 in the test at the end of the chapter, then the question says that there are 11 pairs of data – so n = 11 !!

4. says

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5. says

GOT IT! EXCELLENT! HAVE A HIGHER CHANCE AT PASSING EXAMS! THIS IS DUE TO THE FACT THAT I HAD VERY LIMITED TIME. THE LECTURES ARE REALLY GOOD. UNDERSTOOD IT SO WELL!