Babcock and Marks (2010) review survey data from 2003-2005 and obtained an average of µ = 14 hours per week spent studying by full-time students at four- year colleges in the United States. To determine whether this average has changed in recent years, a researcher selected a sample of n = 64 of today's college students and obtained an average of M = 12.5 hours. If the standard deviation for the distribution is o = 4.8 hours per week does this sample indicate a significant change in the number of hours spent studying? Use the two-tailed test with a = .05.

The ages of a group of 134 randomly selected adult females have a standard deviation of 18.2 years. Assume that the ages of female statistics students have less variation than ages of females in the general population, so let o = 18.2 years for the sample size calculation. How many female statistics student ages must be obtained in order to estimate the mean age of all female statistics students? Assume that we want 98% confidence that the sample mean is within one-half year of the population mean. Does it seem reasonable to assume that the ages of female statistics students have less variation than ages of females in the general population? The required sample size is 7194 . (Round up to the nearest whole number as needed.) Does it seem reasonable to assume that the ages of female statistics students have less variation than ages of females in the general population? A. No, because there is no age difference between the population of statistics students and the general population. B.…

QUESTION 7 Suppose that the average number of miles that a car is driven in the first three years is 41,500. To determine whether leased cars are driven more than "average", 25 leased cars were sampled and the average number of miles on the leased cars was 43,780 with a standard deviation of 10,520. To determine whether the average number of miles on leased cars is statistically significantly greater than the number of miles on other cars (using the 5% level of significance), what is the critical value? (please round your answer to 3 decimal places)

20)   Based on a recent​ study, the pH level of the arterial cord​ (one vessel in the umbilical​ cord) is normally distributed with mean 7.35 and a standard deviation of 0.19. Find the percentage of preterm infants who have the following arterial cord pH levels. a. pH levels between 7.00 and 7.50. b. pH levels over 7.43.   round the answer to two decimal places

In a mid-size company in Tucson, the distribution of the number of phone calls answered each day by each of the 12 receptionists is bell-shaped and has a mean of 53 and a standard deviation of 9. Using the empirical (68-95-99.7) rule, what is the approximate percentage of daily phone calls numbering between 35 and 71? Caution: Using tables or Excel for this may produce a wrong answer. Use the 68-95-99.7 rule. Answer =  % . (Enter your answer as a percent, but do not enter the percent symbol. Do not enter in decimal form or round your answer. For example, enter 93.8 for 93.8%, not 0.939)

The ages of a group of 134 randomly selected adult females have a standard deviation of 18.2 years. Assume that the ages of female statistics students have less variation than ages of females in the general population, so let o = 18.2 years for the sample size calculation. How many female statistics student ages must be obtained in order to estimate the mean age of all female statistics students? Assume that we want 98% confidence that the sample mean is within one-half year of the population mean. Does it seem reasonable to assume that the ages of female statistics students have less variation than ages of females in the general population? The required sample size is. (Round up to the nearest whole number as needed.)

The ages of a group of 159   randomly selected adult females have a standard deviation of 17.1   years. Assume that the ages of female statistics students have less variation than ages of females in the general​ population,so let sigma equals17.1   years for the sample size calculation. How many female statistics student ages must be obtained in order to estimate the mean age of all female statistics​ students? Assume that we want 98 ​% confidence that the sample mean is within​ one-half year of the population mean. Does it seem reasonable to assume that the ages of female statistics students have less variation than ages of females in the general​ population?

The hotel industry has been greatly impacted by the COVID-19 pandemic. Suppose that traditionally the percentage of available hotel rooms that are occupied each night follows a normal distribution with a mean of 56.3 and a standard deviation of 14.3. Since March of 2020 there have been very few days with an above average hotel Occupancy percentage. Based on the distribution above, what must the hotel occupancy percentage be to fall in the top 1.19% of the distribution?