NASA is conducting an experiment to find out the fraction of people who black out at G forces greater than 6. Suppose a sample of 543 People is drawn. Of these people, 217 passed out at G forces greater than 6. Using the data, estimate the proportion of people who pass out at more than 6 Gs. Enter your answer as a fraction or a decimal number rounded to three decimal places.

A technician working for the Chase-National Food Additive Company would like to estimate the preserving ability of a new additive. This additive will be used for Auntie’s brand preserves. Based on past tests, it is believed that the time to spoilage for this additive has a standard deviation of 8 days. To be 95% confident of the true mean time to spoilage, what sample size will be needed to estimate the mean time to spoilage with an accuracy of one day?

The electric cooperative needs to know the mean household usage of electricity by its non-commercial customers in kWh per day. They would like the estimate to have a maximum error of 0.13 kWh. A previous study found that for an average family the standard deviation is 2.1 kWh and the mean is 15.8 kWh per day. If they are using a 99% level of confidence, how large of a sample is required to estimate the mean usage of electricity? Round your answer up to the next integer.

Lesson Review question Chapter 7 Hawkeslearning - MyMathLab Questions and Answers

Qn1. Trucks in a delivery fleet travel a mean of 120 miles per day with a standard deviation of 19 miles per day. The mileage per day is distributed normally. Find the probability that a truck drives less than 146 miles in a day. Round your answer to four decimal places.
Answer: - If you would like to look up the value in a table, select the table you want to view, then either click the cell at the intersection of the row and column or use the arrow keys to find the appropriate cell in the table and select it using the Space key.

Qn2. Find the value of z such that 0.13 of the area lies to the left of z. Round your answer to two decimal places.

Qn3. Find the value of z such that 0.03 of the area lies to the right of z. Round your answer to two decimal places.

Qn4. Calculate the standard score of the given X value, X=89.7, where μ=88.2 and σ=89.4 and indicate on the curve where z will be located. Round the standard score to two decimal places.

Qn5. Consider the probability that no fewer than 75 out of 109 students will not graduate on time. Assume the probability that a given student will not graduate on time is 98% .Specify whether the normal curve can be used as an approximation to the binomial probability by verifying the necessary conditions.

Qn6. Find the area under the standard normal curve between z=−0.75 and z=1.83. Round your answer to four decimal places, if necessary.

Qn7. Consider the probability that greater than 99 out of 159 flights will be on-time. Assume the probability that a given flight will be on-time is 61%. Approximate the probability using the normal distribution. Round your answer to four decimal places.

Qn8. The Arc Electronic Company had an income of 54 million dollars last year. Suppose the mean income of firms in the same industry as Arc for a year is 40 million dollars with a standard deviation of 9 million dollars. If incomes for this industry are distributed normally, what is the probability that a randomly selected firm will earn more than Arc did last year? Round your answer to four decimal places.

Qn9. Find the value of z such that 0.9722 of the area lies between −z and z. Round your answer to two decimal places.

Qn10. A soft drink machine outputs a mean of 28 ounces per cup. The machine's output is normally distributed with a standard deviation of 2 ounces. What is the probability of filling a cup between 30 and 31 ounces? Round your answer to four decimal places.

Qn11. Consider the probability that fewer than 38 out of 542 computers will crash in a day.
Choose the best description of the area under the normal curve that would be used to approximate binomial probability.

Qn12. A psychology professor assigns letter grades on a test according to the following scheme.
A: Top 13% of scores
B: Scores below the top 13% and above the bottom 57%
C: Scores below the top 43% and above the bottom 22%
D: Scores below the top 78% and above the bottom 8%
F: Bottom 8% of scores
Scores on the test are normally distributed with a mean of 71 and a standard deviation of 8.1. Find the numerical limits for a C grade. Round your answers to the nearest whole number, if necessary.