Suppose the finishing times for cyclists in a race are normally distributed. If the population standard deviation is 16 minutes, what minimum sample size is needed to be 90% confident that the sample mean is within 5 minutes of the true population mean?

The main purpose of inferential statistics is to know whether: random sampling error occurs. the sample represents the population. the sample is randomly selected. the population size is larger than sample size.

In hundreds of studies with many thousands of participants, first-born children scored better than second born children on tests of cognitive ability. Data based on previous research provides mean scores of 469 for first born and 456 for second born. The cognitive ability standard deviation is 100. Find effect size and interpretation.

Assume that adults have iq scores that are normally distributed with a mean of 97.9 and a standard deviation 16. Find the first quartile Q1, what is the iq score separating the bottom 25% from the top 75%.

Suppose that the score on a reading test are normally distributed within a mean of 70 and a standard deviation of 10. What proportion of the individual score is more than 85 on the test?

Suppose a new drug is intended to improve walking distance in patients with Parkinson’s Disease. A researcher measures patients’ walking distance in feet before and after trying the drug for 9 weeks. What type of statistical test

Suppose that you randomly survey death records for people born in 1900 in Louisiana and compared the life span of two different ethnicities. Of the 109 individuals sampled from ethnicity 1, the mean life span was 45.5 years with a standard deviation of 18.2 years. Of the 105 individuals sampled from ethnicity 2, the mean life span was 44.9 years with a standard deviation of 11.4 years. Conduct a hypothesis test with a 10% level of significance to see if the mean life spans in Louisiana were the same for the two ethnicities. Step 1: State the null and alternative hypotheses. Ho: µ1 – µ2 =v Ha:H1 – µ2 # v (So we will be performing a two-tailed ♥ test.)

The distribution of sample means will always be normal if taken from a normal population. True or False?

You are estimating the mean blood plasma volume in male firefighters and you’ve decided to usethe sample mean, ?̅, as the estimator. Explain why ?̅ has a normal sampling distribution

The results of a common standardized test used in psychology research is designed so that the population mean is 175 and the standard deviation is 10. A subject earns a score of 183. What is the z-score for this raw score?