Suppose that the duration of trouble-free operation of a new vacuum cleaner is normally distributed with mean 500 days and a standard deviation of 81 days. The research department randomly selects 36 customers who bought these vacuum cleaners and records duration (in days) of trouble-free operation.
What is the standard error of sample mean?
Suppose that the duration of trouble-free operation of a new vacuum cleaner is normally distributed with...
Suppose that the duration of trouble-free operation of a new vacuum cleaner is normally distributed with mean 500 days and a standard deviation of 81 days. The research department randomly selects 36 customers who bought these vacuum cleaners and records duration (in days) of trouble-free operation. The standard error of the sample mean is days (1 decimal place). The probability that the average duration of trouble-free operation time is between 480 days and 530 days is (4 decimal places).
It is known that the duration of trouble-free operation of a new vacuum cleaner is normally distributed with a standard deviation of 98 days. The research department randomly selects 25 customers who bought these vacuum cleaners and records the duration of trouble-free operation to construct a 95% confidence interval for population mean duration of trouble-free operation. The critical value needed is _________ a. 1.96 b. 1.645 c. 2.064 d. Insufficient information to compute the critical value
Suppose that the duration of a particular type of criminal trial is known to be normally distributed with a mean of 21 days and a standard deviation of 8 days If one of the trials is randomly chosen, find the probability that it lasted more than 27 days. (Round your answer to four decimal places.) Write the probability statement. P
Suppose that the duration of a particular type of criminal trial is known to be normally distributed with a mean of 23 days and a standard deviation of 6 days. If one of the trials is randomly chosen, find the probability that it lasted more than 26 days. Write the probability statement and the amount of this probability. Use 4 decimal places in your probability. ex. of probability statements: P(a < X < b), P(X < a), P(X > a)
Suppose that the duration of a particular type of criminal trial is known to be normally distributed with a mean of 22 days and a standard deviation of 4 days. Let X be the number of days for a randomly selected trial. Round all answers to 3 decimal places where possible. a. What is the distribution of X? X ~ N( _____ , _____) b. If one of the trials is randomly chosen, find the probability that it lasted at...
Suppose that the time duration of a minor surgery is approximately normally distributed with mean equal to 800 seconds and a standard deviation of 40 seconds. Find the probability that a random sample of 16 surgeries will have average time duration of less than 775 seconds. Use the central limit theorem 9-
Suppose the lengths of the pregnancies of a certain animal are approximately normally distributed with a mean of μ=188 days and a standard deviation of σ=13 days. What is the probability that a randomly selected pregnancy lasts less than 184 days?
Suppose the lengths of the pregnancies of a certain animal are approximately normally distributed with mean mu equals 259 days and standard deviation sigma equals 18 days what is the probability that a randomly selected pregnancy lasts less than 252 days?
Suppose that the underlying population is normally distributed. Suppose further that a random sample of 36 observations on a single variable has a sample mean of 4 and a sample standard deviation of 3. That standard error of the sampling distribution is 0.75 2 0.5 1
8. Suppose the scores of students on an exam are normally distributed with mean u = 17.6 and standard deviation o = 4.9. (a) Determine the distribution of the sample mean score for a randomly selected sample of 36 students who took the exam. (b) Find the probability that the sample mean score will be less than 20 for a sample of 36 randomly selected students. (c) How large a sample size would be required to ensure that the probability...