EXERCISE 18 Mean Standard Deviation And 95 And 99 Of The Normal Curve

We know that +/- 1.96 standard deviations from the mean will contain 95% of the values. So, we can get the standard deviation by:

2. In order to determine the average amount spent in November on Amazon.com a random sample of 144 Amazon accounts were selected. The sample mean amount spent in November was $250 with a standard deviation of $25. Assuming that the population standard deviation is unknown, what is a 95% confidence interval for the population mean amount spent on Amazon.com in November?

(c) The mean of the sample and the value of Z with an area of 5% in the left tail.

9. Assume the weight, W, of a randomly selected adult has a normal distribution with a mean

If John gets an 90 on a physics test where the mean is 85 and the standard deviation is 3, where does he stand in relation to his classmates? (he is in the top 5%, he is in the top 10%, he is in the bottom 5%, or bottom 1%)

Body weight expressed as a percentage of ideal in an SRS of n = 9 girls selected at random are as follows {114, 100, 104, 94, 114, 105, 103, 105, 96}. Calculate a 95% confidence interval for the population mean µ.

5. Give the standard deviation for the mean and median column. Compare these and be sure to identify which has the least variability?

Topics Distribution of the sample mean. Central Limit Theorem. Confidence intervals for a population mean. Confidence intervals for a population proportion. Sample size for a given confidence level and margin of error (proportions). Poll articles. Hypotheses tests for a mean, and differences in means (independent and paired samples). Sample size and power of a test. Type I and Type II errors. You will be given a table of normal probabilities. You may wish to be familiar with the follow formulae and their application.

18. Suppose that the scores of architects on a particular creativity test are normally distributed. Using a normal curve table, what percentage of architects have Z scores:

2. For the following set of scores, fill in the cells. The mean is 74.13 and the standard deviation is 9.98.

Garner, David. “The 1997 Body Image Survey Results.” Overall men and women are affected everyday by what social media has to say. It makes people unhappy with who they are and what they look like. Women and men are feeling ashamed about things that really aren't under their control.

This raises the question about gender difference and the concept of body image and prevalence of

Body image is a major concern amongst the majority, primarily the youth of the female population, ranging from as young as five years old to tertiary students, ’74.4% of the normal-weight women stated that they thought about their weight or appearance ‘all the time’ or ‘frequently’’ (Brown University, unknown).

In this research, thematic analysis distinguished the gender difference among age-related and body image concerns. Four sub-categories emerged from the results; the first two categories displayed conceptualization of the body. Men described their bodies as a unit and had a single evaluation of their bodies. Whereas women’s responds were negative and positive, the responds were very detailed and focused more on parts of the body.

The 95% confidence interval for the population mean is 66,438 to 80,241. This means that there is a 95% confidence that this interval has the population mean.