# Thread: Homework help with Confidence Intervals & Estimating Probability Proportions?

1. ## Homework help with Confidence Intervals & Estimating Probability Proportions?

I'm super lost on a few sets of my statistics homework and wondering if anyone can walk me through this so I can finish the rest of the questions as well!

"A simple random sample size n is drawn. The sample mean is found to be 35.1 and the sample standard deviation is found to be 8.7?

A) Construct a 90% confidence interval for μ if the sample size, n, is 40

B) If the sample size is n = 18, what conditions must be satisfied to compute the confidence interval?"

I really really appreciate any help! Thank you!

2. ## Re: Homework help with Confidence Intervals & Estimating Probability Proportions?

Hi there and welcome!

See here for our homework policy. Basically, the idea is that you show us what you've tried first.

So what have you tried to tackle this problem? What kind of material have you covered?

3. ## Re: Homework help with Confidence Intervals & Estimating Probability Proportions?

These should be easy ones for your at this point:

A) Look up formula for calculating confidence interval and use 1.645 as the alpha/2 term in the calculation.

B) Think symmetry, what distributions go with that idea.

Where does the probability proportions come into play?

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