# z Confidence intervals for the Mean

Confidence intervals for the mean are a vital statistical tool used to estimate the range within which the true population mean lies with a certain level of confidence. They provide a measure of uncertainty around the sample mean, allowing researchers to infer about the population mean based on sample data. Calculated using sample statistics and the standard error of the mean, confidence intervals help quantify the precision of estimates and aid in drawing robust conclusions from data analysis. Understanding and interpreting confidence intervals are fundamental in various fields, including economics, medicine, and social sciences.

Questions

- What is the Z score for 95%?
- What is the area between z= 2.11 and z = 2.49?
- The question in the picture below..?
- In a class test where the mean was 62% and the standard deviation 12.6%, bob received 50%. What is his z-score?
- If the mean, actual observed values, and standard deviation are multiplied by #2#, does the z-score stay the same?
- If 1.25% of the area lies to the left of 42, and 1.25% right to the right of 48, what is the mean and standard deviation of the normal distribution?
- ? Find the percent of a standard normal model found in the region : #z<1.13#
- When 339 college students are randomly selected and surveyed, it is found that 111 own a car. How do you construct a 95% confidence interval for the percentage of all college students who own a car?
- What is the area under the standard normal curve that lies between #Z=0# and #Z=1.51#?
- What is the z-number associated with a 91% level of confidence? (In two decimal places)
- How do you find the z score of a percentile?
- What is the interquartile range of the data set: 46, 9, 48, 96, 61, 84, 29, 1, 82, 5, 34?
- What is the z value for a 90, 95, and 99 percent confidence interval?
- In the Z-score formula, can the standard error measurement be used instead of standard deviation?
- A distribution has a standard deviation of #sigma=8#. How do you find the z-score below the mean by 8 points?
- What is 'z' if the confidence interval is 80%?
- What is 'z' if the confidence interval is 89%?
- How do you find the z-score that has 93.82% of the distribution's area to its left?
- A survey of 144 retail stores revealed that the average price of a microwave was $375 with a standard error of $20. What is the 80% confidence interval of the true average price of the microwave?
- The mean height of 8 male subjects in a room is 177.62 cm. One subject leaves the room. The mean height is now 176.42 cm. What is the height of the male who left the room?