Why Can't I Get These VERY Basic Calculations

eliotjconnor  wrote:  ``this is NOT an issue of rounding or decimal places``

Yes, it is.  But I think "you" misunderstand what the rounding issue is.

(I put "you" in quotes because perhaps it is really an explanation that someone offered.)

You are correct that it is __not__ a rounding issue with your Excel calculations.

Instead, it is a rounding issue with the numbers that the professor presents.  Let's look at your examples.

1. ``E3 should be found by multiplying .069 by 3. That’s .207. Why does he have .206? ``

So, we can conclude that the actual "p" value is between 0.0685 and 0.06949...9, which the professor rounded to 0.069.

For simplicity, I'll say "between 0.0685 and 0.0695" with that understanding that I mean 0.0685 <= p < 0.0695.

And in fact, 0.206 (sic) is actually a value between 0.2055 and 0.2065.

That is, 0.2055 <= 3*p < 0.2065

So 0.2055/3 <= p < 0.2065/3.  So 0.0685 <= p < 0.0688333333333333

2. ``F3 should be .117*4, which should be .468, yet he has .469.

    F4 should be 1.872, as it’s the square of 4 multiplied by .117. Yet he’s got 1.875``

So, 0.117 (sic) can be a value between 0.1165 and 1175.  0.469 (sic) is between 0.4685 and 0.4695.  And 1.875 (sic) is between 1.8745 and 1.8755.  Thus:

0.4685 <= 4p < 0.4695 implies 0.4685/4 <= p < 0.4695/4.

So 0.117125 <= p < 0.117375

1.8745 <= 16*p < 1.8755 implies 1.8745/16 <= p < 1.8755/16

So 0.11715625 <= p < 0.11721875

The latter is the better range for "p" because it is more restrictive.

3. We might work through similar calculations for each "p" value.

Unfortunately, then there are many combinations of the "p" ranges that might sum to 1.

(And many more combinations that do not.  Those would be invalid combinations.)

We cannot know which combination is best.

If all of this is very daunting for you, I sympathize.  You are struggling to learn statistics and Excel.  It is unfair that the professor foisted another burden on you, namely sussing out his misrepresentations.

4. You wrote:  ``don't tell me to ask the professor [....] I'm not here for life advice.``

Fair enough.  But I think this might be valuable feedback for the professor.  And he/she might provide you with the more accurate numbers so that you can proceed with the assignment with confidence.

More importantly, hopefully that feedback might avoid such confusion in future assignments.  (Although I doubt it.)

5. ``The calculation that he uses to get “m” is =SQRT(L4-L3^2) [....] I think maybe he is mixing up the value for “l” in the equation?``

Excellent intuition!  Give yourself some credit. (smile)

Speaking from personal experience, I'm afraid that is a very common mistake that we all make with our examples.  We start with one design (the sums in column L, in this case), then we "simplify" our design, but forget to update all of the formulas.

Again, I understand your frustration.  It's an unfair burden while you are struggling with what you're supposed to be learning.   But I'm sorry to say, as Forrest Gump did:  (sh)it happens. (sigh)

6. ``if you do use I3 and I4 for [...m...] I get 2.198 and he gets 2198``

You mean, if you use values that the professor presents in I3 and I4.

I think it is "obvious" that the professor got sloppy and omitted the decimal point.

Or "m" should be 1000*SQRT(...).  But I don't really believe that.

But note:  we really get 2.19790240911647, not 2.198.  So you committed the same confusing mistake that the professor did:  you presented a rounded number without telling us.  (wink)

The bottom line is:  Re ``I'm here for Excel advice``, it looks to me like you've nailed the Excel usage.  Congrats!