The fan blades on commercial jet engines must be replaced when wear on these parts indicates too much variability to pass inspection. If a single fan blade broke during operation, it could severely endanger a fight. A large engine contains thousands of fan blades, and safety regulations require that variability measurements on the populatio of all blades not exceed ²-0.18 mm². An engine inspector took a random sample of 71 fan blades from an engine. She measured each blade and found a sample variance of 0.31 mm². Using a 0.01 level of significance, is the inspector justified in claiming that all the engine fan blades must be replaced? (a) What is the level of significance? State the null and alternate hypotheses. ⒸM₂²0.181 ₂:0² < 0.18 ⒸM₂²0.181 ₂ ²0.10 ⒸM²0.10 M₁₂ 0²-0.18 Ho: ²0.18 ₂:²0.10 (b) Find the value of the chi-square statistic for the sample. (Round your answer to two decimal places.) What are the degrees of freedom? What assumptions are you making about the original distribution? O We assume a normal population distribution. O We assume a binomial population distribution. O We assume a uniform population distribution. We assume a exponential population distribution. (c) Find or estimate the P-value of the sample test statistic OP-value> 0.100 O 0.050 < P-value < 0.100 O 0.025 Palue 0.050 O 0.010 P-value < 0.025 O 0.005 P-value < 0.010 OP-value < 0.005

Average speed on a freeway is  80  mph.   Among all vehicles 65% drive 8 miles above the speed limit of 70 mph.   34 What fraction drive within          ± 5 mph from the mean speed? a 0.7327             b 0.6978             c 0.6646             d 0.6330

A factory manager knows that the pieces produced by their machine will have lengths which are normally distributed, with mean 10 cm and standard deviation 4 mm.  If this is true, then 95% of the pieces produced will have lengths between What?

Researchers wanted to determine if carpeted rooms contained more bacteria than uncarpeted rooms. To determine the amount of bacteria in a room, researchers pumped the air from the room over a Petri dish at the rate of 1 cubic foot per minute for eight carpeted rooms and eight uncarpeted rooms. Colonies of bacteria were allowed to form in the 16 Petri dishes. The results are given in the table below. Assume the distribution to be approximately normal. Do carpeted rooms have more bacteria than uncarpeted rooms?   Carpeted Rooms Uncarpeted Rooms 11.7 12.0 8.2 8.3 7.1 3.8 13.1 7.3 10.6 12.0 10.1 11.1 14.8 10.3 14.0 13.7   What is the critical value(s) for this hypothesis test if group 1 is the carpeted rooms and group 2 is the uncarpeted rooms. 1.895 2.306 2.365 1.833 1.860

Assume that the readings on the thermometers are normally distributed with a mean of 0° and standard deviation of 1.00°C. Assume 2.1​% of the thermometers are rejected because they have readings that are too high and another 2.1​% are rejected because they have readings that are too low. Draw a sketch and find the two readings that are cutoff values separating the rejected thermometers from the others.

Solve this problem to find the sample standard deviation

The population mean will always be the same as the mean of all possible that can be computed from samples of size 27. True O False

The weights of people in a certain population are normally distributed with a mean of 159 lb and a standard deviation of 24 lb. Determine the sampling distribution of the mean for samples of size 5.