Question

For a specific year, the average score on the SAT Math test was 525. The variable is

normally distributed, and the population standard deviation is 105. A superintendent wishes to see if her students scored significantly higher than the national average on the test. She randomly selected 45 student scores and the mean for this sample was 545. At α = 0.05 , is there enough evidence to support the claim?

μ = _________ σ = _________ n = _________ x̄ = ________

H0=_____ H1=______

▪ Find the critical value(s) from Table E and draw the graph

▪ Compute the z test value

▪ Reject or not reject:

▪ Summarize the results:

Exercise 2. Find the specific areas

Find the area under the standard normal distribution to the left of z=2.25

Find the area under the standard normal distribution to the right of z=−1.25

Find the area under the standard normal distribution between z=−1.5 and z=1.5   

Exercise 3. True or false

__________ If the correlation is positive, means that one variable causes the other.

__________ The z can be used when n ≥ 20.

__________ The z-test can be used when the population is normally distributed and σ is known.

__________ The correlation coefficient could be negative.

__________ Statistic is the science of conducting studies to collect, organize, summarize, analyze, and draw conclusions from data.

__________ Inferential Statistics consist on generalizing from sample to populations.

Exercise 4. To qualify for a police academy, candidates must score in the top 25% on a general abilities test.

Assume the test scores are normally distributed and the test has a mean of 300 and a standard of 25. Find the lowest possible score to qualify.

please need help will give great comments and feedback

Answer 1