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# Two Super Quick S1 questions Watch

1. Found last part to be 18.2 and then I tried to use linear interpolation but it didn't seem to work :/

Attachment 527695527699

I get that Syy rises, but why doesn't Sxy rise if y rises?

(only need a hand on the last part of each question)
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2. (Original post by creativebuzz)
I get that Syy rises, but why doesn't Sxy rise if y rises?
Because if the change in y is negated by the change in and hence this means that the term in the summation doesn't really change when summed over, and hence doesn't change.
3. (Original post by Zacken)
Because if the change in y is negated by the change in .
But Syy increases so surely the change in y is not negated by the change is y bar
4. (Original post by Zacken)
Because if the change in y is negated by the change in and hence this means that the term in the summation doesn't really change when summed over, and hence doesn't change.
Sorry to be so annoying but would you mind explaining?
5. (Original post by creativebuzz)
Sorry to be so annoying but would you mind explaining?
for the new name, x-xbar is 0, meaning Sxy doesn't change because when multiplying x-xbar by y-ybar for the new name, you get zero so the overall sum remains unchanged
6. (Original post by veejn)
for the new name, x-xbar is 0, meaning Sxy doesn't change because when multiplying x-xbar by y-ybar for the new name, you get zero so the overall sum remains unchanged
Ohhh now I understand, thanks!

Would you mind giving me a hand on the first picture I posted in the first post of this thread? (I only need help on the last part of that question) (the tomato one)

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