A machine is designed to manufacture bolts with a diameter of 15 mm. 23 bolts are examined, and it's found they have a mean diameter of 15.1 mm, with a standard deviation of .37 mm. To a 2.5% level of significance, can it be asserted that, in general, the standard deviation of the bolts is over .25 mm? [Assume that the bolt diameters are normally distributed.]

The data table contains waiting times of customers at a bank, where customers enter a single waiting line that feeds three teller windows. Test the claim that the standard deviation of waiting times is less than 2.12.1 minutes, which is the standard deviation of waiting times at the same bank when separate waiting lines are used at each teller window. Use a significance level of 0.050.05. Complete parts (a) through (d) below. LOADING... Click on the icon to view the data. 7.9 6.4 7.3 6.7 7.3 6.4 6.9 7.1 8.3 6.2 6.3 7.2 8.8 6.1 8.9 7.5 7.5 7.6 6.1 7.6 7.3 7.7 7.9 10.1 7.1 6.1 6.5 6.6 6.7 6.9 6.6 6.8 6.9 14.6 6.6 7.2 7.7 7.5 7.6 6.3 13.9 7.2 8.7 7.5 6.1 6.3 7.4 6.1 6.7 6.3 9.1 8.3 6.4 7.9 7.5 8.5 7.8 6.3 6.5 6.5   a. Identify the null and alternative hypotheses. Choose the correct answer below.     A. Upper H 0 : sigma greater than or equals 2.1H0: σ≥2.1 minutes Upper H Subscript Upper A Baseline : sigma less than 2.1HA: σ<2.1 minutes   B. Upper H 0 : sigma…

A survey found that women's heights are normally distributed with mean 63.4 in. and standard deviation 2.5 in. The survey also found that men's heights are hormally distributed with mean 68.3 in. and standard deviation 3.7 in. Most of the live characters employed at an amusement park have height requirements of a minimum of 57 in. and a maximum of 62 in. Complete parts (a) and (b) below. a. Find the percentage of men meeting the height requirement. What does the result suggest about the genders of the people who are employed as characters at he amusement park? The percentage of men who meet the height requirement is %. Round to two decimal places as needed.)

Based on a recent​ study, the pH level of the arterial cord​ (one vessel in the umbilical​ cord) is normally distributed with mean 7.27and standard deviation of 0.11. 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 7.35.   a. The percentage of arterial cord pH levels that are between 7.00and 7.50 is __________​%. ​(Round to two decimal places as​ needed.)   b. The percentage of arterial cord pH levels that are over 7.35 is _______%. ​(Round to two decimal places as​ needed.)