You want to obtain a sample to estimate how much parents spend on their kids birthday parties. Based on previous study, you believe the population standard deviation is approximately σ=44.7σ=44.7 dollars. You would like to be 98% confident that your estimate is within 1.5 dollar(s) of average spending on the birthday parties. How many parents do you have to sample?

Consider the following data: x 4 5 6 7 8 P(X = x) 0.2 0.2 0.1 0.2 0.3 Step 3 of 5: Find the standard deviation. Round your answer to one decimal place. Copy Data

Scores on the Wechsler Adult Intelligence Scale for the 2020 to 3434 age group are approximately Normally distributed with a mean of 110 and a standard deviation of 15. How high must a person score to be in the top 5%5% of all scores? Enter your answer as a whole number.

Please answer this question below correctly,  Also while reading the question below carefully.

A population has a mean μ = 70 and a standard deviation o=36. Find the mean and standard deviation of a sampling distribution of sample means with sample size n = 81. H=(Simplify your answer.) = (Simplify your answer.)

You have a normal population with a mean of 1000 and a standard deviation of 100.Determine the scores associated with the following percentiles:   50% 45% 95% 5% 77%

To celebrate the end of final exams you and friends head to a favorite downtown restaurant. You find a street parking spot with a maximum of two hours. If you stay longer than two hours, you risk having your car towed away. No one has a watch or cellphone but you remember that the average time you spent at the same restaurant over your previous 16 visits is 1.5 hours, and you estimate the sample standard deviation to be about 20 minutes. You also need to factor in that it takes 8 minutes to walk to the restaurant and 8 minutes to walk back to your car (you are very certain about these two durations). (a) One of your friends is really worried that you won’t get back to the car in time and so the car might be towed away! Does your friend have good reason to be worried? Test at a 5% significance level whether the mean total time will be less than two hours. (b) You decide to leave the car parked at the street spot but it gets towed. What type of error have you committed?

z Scores LeBron James, one of the most successful basketball players of all time, has a height of 6 feet 8 inches, or 203 cm. Based on statistics from Data Set 1 “Body Data” in Appendix B, his height converts to the z score of 4.07. How many standard deviations is his height above the mean?

A normal population has mean u = 50 and standard deviation o = 5. What is the 80th percentile of the population? Use the TI-84 Plus calculator. Round the answer to at least one decimal place.

Levels of a certain enzyme in the blood have a mean value of 34.0 mg/mL and a standard deviation of 3.5 mg/mL.  Complete the following steps to determine what levels of the enzyme correspond to the top 20% of test results.   Are you calculating the top or bottom 20%? Answer So, which percentage needs to be converted to an area? Answer What is the area that you will look for in the table (four decimal places)? Answer What area will you actually use from the table (four decimal places)? Answer What is the z-score associated with that area (two decimal places)? Answer What is the cutoff level of the enzyme that corresponds to the top 20% of test results? (round to the nearest tenths)   Answer Are values lower or higher than that value also in the top 20%? Answer