# Probability

• Mar 22nd 2010, 08:48 PM
Mur
Probability
μ = 45
σ = 8

Using a normal model, what is the probability that 35 attempts will be less than 43
• Mar 22nd 2010, 08:58 PM
ANDS!
"z=x-u/std"

Never mind that this is a barebones question (whose equivalent might be a fragment sentence in English) but I struggle to find how this question is different fundamentally than the question you just had in regards to calculating the probability of observing a test statistic in a normally distributed population?
• Mar 22nd 2010, 09:05 PM
Mur
I don't quite know how the # of attempts comes in equation
• Mar 22nd 2010, 09:07 PM
ANDS!
Nor would I imagine does anyone else. You haven't provided any context to this problem whatsoever. Do not assume that folks can infer what you mean; too much information is better than too little. Write out the entire problem, and any preceding information so that folks can assist you.
• Mar 22nd 2010, 09:10 PM
Mur
"From past tests, mean = 45 and SD = 8. What is the probability that a group of 35 people will have an average index score less than 43 on a test."

i don't quite see how that changes the question originally stated.
• Mar 22nd 2010, 09:14 PM
ANDS!
Context. I mean you're just finding a z-statistic like I said in my original post (because thats all these normal questions will ever ask you to do), but it does help to provide the entire problem and not just the information you think might be relevant to the problem.
• Mar 22nd 2010, 09:25 PM
Mur
Sorry for the confusion ANDS! and thanks for the input.