Math Is Fun Forum

mahipal51

Guest

statistics and probability

suppose you know the mean = 12 and the standard deviation = 20 for a white noise process. The last observations were -5, 11, 17. What is your best guess for the next value?

1.- 17

2.- 20

3.- 7.67

4.- 12

Bob

Administrator

Registered: 2010-06-20

Posts: 10,640

Re: statistics and probability

hi mahipal51

Welcome to the forum.

I would work like this.

11 + 17  -5 = 23

Let the next guess be x.

Then we want 11 + 17 - 5 + x = 12 times 4 = 48.  => x = 25

Bob

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irspow

Member

Registered: 2005-11-24

Posts: 1,055

Re: statistics and probability

I am curious what the correct answer was for the OP. Your solution is rational but was not an available choice. I looked at it taking both the mean and standard deviation into account simultaneously.

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I am at an age where I have forgotten more than I remember, but I still pretend to know it all.