Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Mr. Roegner Statistics Review for Unit #5 Test Formulas: x 1.a) x n z x x x np npq What does a z-score tell us? b) In your own words, how do we find a z-score? 2. Final exam scores are normally distributed with a mean of 83 and a standard deviation of 7. Jimmy’s exam score on the final is 75. Find the z-score corresponding to this value. 3. Use the standard normal distribution to find P(0<z<1.55). Shade the indicated region. 4. Use the standard normal distribution to find P(z < -0.85 or z > 0.85). Shade the indicated region. 5. Use the standard normal distribution to find P(z>-1.28). Shade the indicated region. 6. The ACT and SAT tests are normally distributed. The mean scores for the ACT are 21 with a standard deviation of 5, while SAT has a mean of 1250 with a standard deviation of 120. Bob scored a 24 on the ACT and scored a 1320 on the SAT. If we use z-scores to compare, which test did he have a better score on? Explain. 7. Find the z-score with a cumulative area to the left of 0.7307. 8. Assume the starting salaries of elementary school teachers in the United States are normally distributed with a mean of $31,000 and a standard deviation of $3,400. What is the cutoff salary for teachers in the top 15% ? 9. The average number of pounds of red meat a person consumes each year is 176 with a standard deviation of 21 pounds. If a sample of 50 individuals is randomly selected, find the probability that the mean of the sample will be more than 177 pounds. 10. Assume that the heights of men are normally distributed with a mean of 69.7 inches and a standard deviation of 2.9 inches. If 50 men are randomly selected, find the probability that they have a mean height greater than 69.9 inches. 11. According to government data, the probability that an adult was never married is 21%. You randomly select 40 adults and ask if he or she was ever married. Decide whether you can use the normal distribution to approximate the binomial distribution. If so, find the mean and standard deviation. If not, explain why. 12. According to school data, 14% of the students at LHS are left-handed. You randomly select 30 students and ask if they are left-handed. Decide whether you can use the normal distribution to approximate the binomial distribution. If so, find the mean and standard deviation. If not, explain why. Use the normal distribution to approximate the binomial distribution for 13 and14. 13. The failure rate in a college statistics class is 19%. In a class of 30 students, find the probability that a) more than 6 students fail. b) exactly 5 students fail. 14. A student answers all 36 questions on a multiple-choice test by guessing. Each question has four possible answers, only one of which is correct. Find the probability that the student gets between 8 and 12 correct, inclusive.