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# Calculating Probabilities without Standard Deviation

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I need some guidance in how to calculate probabilities without knowing the std deviation.

Population = 3005

calculate P(x-bar > 50.8) for sample size of n = 253

calculate P(x-bar > 50.6) for sample size of n = 134

calculate P(x-bar > 51) for sample size of n = 119

Then combine the two probabilities 51 and 50.6 into one using the concept of independent events.

https://brainmass.com/statistics/probability/calculating-probabilities-standard-deviation-182198

#### Solution Preview

I need some guidance in how to calculate probabilities without knowing the std dev. I am struggling with the correct formula...

Population = 3005

(1) calculate P(x-bar > 50.8) for sample size of n = 253

(2) calculate P(x-bar > 50.6) for sample size of n = 134

(3) calculate P(x-bar > 51) for sample size of n = 119

Then combine the two probablities 51 and 50.6 into one using the concept of independent events.

Guidance would be appreciated.

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Hi, regarding your questions, I would like to give you the following guidance.

First of all, since you did not provide any detailed information for each of samples (with size n=253, 134, and 119, respectively), I could not provide with you a ...

#### Solution Summary

The solution calculates probabilities without standard deviation.

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