You want to obtain a sample to estimate a population mean. Based on previous evidence, you believe the population standard deviation is approximately σ=62.5σ=62.5. You would like to be 95% confident that your estimate is within 1.5 of the true population mean. How large of a sample size is required? Round up to nearest whole number.
Inverse Normal Distribution
The method used for finding the corresponding z-critical value in a normal distribution using the known probability is said to be an inverse normal distribution. The inverse normal distribution is a continuous probability distribution with a family of two parameters.
Mean, Median, Mode
It is a descriptive summary of a data set. It can be defined by using some of the measures. The central tendencies do not provide information regarding individual data from the dataset. However, they give a summary of the data set. The central tendency or measure of central tendency is a central or typical value for a probability distribution.
Z-Scores
A z-score is a unit of measurement used in statistics to describe the position of a raw score in terms of its distance from the mean, measured with reference to standard deviation from the mean. Z-scores are useful in statistics because they allow comparison between two scores that belong to different normal distributions.
You want to obtain a sample to estimate a population
Since we know population standard deviation, use z-distribution.
Find z-critical value:
Refer Standard normal table/Z-table OR use excel function "=NORM.S.INV(1-0.025)" to find the critical value of z.
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