Given P(X = 2, Y = 10) = 0.3, P(X = 6, Y = 2.5) = 0.4, and P(X = 10, Y = 0) = 0.3, then COV(XY) is:
A) -12.0. B) 24.0. C) 6.0.
I wish to know if there is any means I can calculate this thing on my Texas BA ii plus. I read somewhere that r*sx*sy should give me the answer but i cannot.
Answer is-12.0
Kindly advise me.
Yes sir, there is a way for that. And you are right that r*Sx*Sy will give you covariance.
Follow these instructions:
Press 2nd button (Yellow one) and number 8 (STAT) simultaneously.
Make sure it is set to Linear (calculator will show you LIN). If not, then keep pressing 2nd button (Yellow one) with enter button (SET) until it shows you the LIN option
Press 2nd button with number 7 (DATA), input all your numbers . Press 2nd button with number 8 (STAT) again.
Press the down arrow button (besides ON/OFF) at top right of the calculator. Keep pressing the down arrow button and it will show you the result for each metric.
If you want to save more time, then use the STORE/RECALL function and store values for r, Sx and Sy. Otherwise, note the values for r, Sx, and Sy manually and multiphy them. You will have your covariance. See the calculator manual for help. They have done it step by step in an example.
It’s highly unlikely that they’ll ask you to calculate covariance on the test.
Its more likely that you’ll be given the covariance and asked to interpret it.