The time spent waiting in the line is approximately normally distributed. The mean waiting time is 5 minutes and the variance of waiting time is 9. Find the probability that a person will wait for more than 2 minutes . Round your answer to four decimal places the waiting time

A professor knows that her statistics students' final exam scores have a mean of 79 and a standard deviation of 12.4. In his class, an "A" is any exam score of 90 or higher. This quarter she has 25 students in her class. What is the probability that 7 students or more will score an "A" on the final exam?

Yoonie is a personnel manager in a large corporation. Each month she must review 16 of the employees. From past experience, she has found that the reviews take her approximately four hours each to do with a population standard deviation of 1.2 hours. Let Χ be the random variable representing the time it takes her to complete one review. Assume Χ is normally distributed. Let x¯x¯ be the random variable representing the mean time to complete the 16 reviews. Assume that the 16 reviews represent a random set of reviews. What causes the probabilities in Exercise 7.3 and Exercise 7.4 to be different?

the statistic X defined as X = 49S 2

Yoonie is a personnel manager in a large corporation. Each month she must review  10  of the employees. From past experience, she has found that the reviews take her approximately  4  hours each to do with a population standard deviation of  1.1  hours. Let  X  be the random variable representing the time it takes her to complete one review. Assume  X  is normally distributed. Let  X¯¯¯  be the random variable representing the mean time to complete the  10  reviews. Assume that the  10  reviews represent a random set of reviews. (a) What is the mean, standard deviation, and sample size? Mean = Standard Deviation = Sample Size = (b) Complete the distributions. Round all decimals to four decimal places. X∼ ( Number, Number)   X¯¯¯∼ ( Number, Number)

The life of light bulbs is distributed normally. The variance of the lifetime is 900 and the mean lifetime of a bulb is 550 hours. Find the probability of a bulb lasting for at least 583 hours. Round your answer to four decimal places

The mean points obtained in an aptitude examination is 111 points with a variance of 400.   What is the probability that the mean of the sample would be greater than 113.1 points if 79 exams are sampled? Round your answer to four decimal places.

The time spent waiting in the line is approximately normally distributed. The mean waiting time is 66 minutes and the variance of the waiting time is 44. Find the probability that a person will wait for more than 33 minutes. Round your answer to four decimal places.

I tried the two last choice both of them are wrong.

The average American gets a haircut every 34 days. Is the average smaller for college students? The data below shows the results of a survey of 15 college students asking them how many days elapse between haircuts. Assume that the distribution of the population is normal. 35, 23, 32, 38, 31, 39, 35, 25, 30, 36, 40, 27, 23, 32, 25 What can be concluded at the the a = 0.10 level of significance level of significance? a. For this study, we should use Select an answer b. The null and alternative hypotheses would be: Ho: ?v Select an answerv Hi: ?vSelect an answerv c. The test statistic ?v = (please show your answer to 3 decimal places.) d. The p-value = (Please show your answer to 3 decimal places.) e. The p-value is 2v a f. Based on this, we should Select an answerv the null hypothesis. g. Thus, the final conclusion is that.. O The data suggest the population mean is not significantly lower than 34 at a = 0.10, so there M 24 3. 4. 5 6. 7 EU