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A random sample of 16 light bulbs with a mean operating life of 300 hours and a standard deviation of 45 hours is picked up from a very large shipment of light bulbs known to have a normally distri
A large university reports that the mean salary of parents of an entering class is $91.600. To see how this compares to his university, a president surveys 28 randomly selected families and finds th
The inside diameter of a randomly selected piston ring is a random variable with mean value 12 cm and standard deviation 0.05 cm. Suppose the distribution of the diameter is normal. (Round your answ
A study of elephants is conducted to determine the average weight of a certain subspecies of elephants. The standard deviation for the population is 500 pounds. At a 80% level, how many elephants ne
The confidence level of an interval estimate of a parameter is the probability that the interval estimate will contain the parameter.
A previous analysis of paper boxes showed that the the standard deviation of their lengths is 9 millimeters. A packer wishes to find the 98% confidence interval for the average length of a box. How
Specify the null and alternative hypotheses to test the hairdresser's claim. Calculate the sample mean revenue and the sample standard deviation.
Question 1: The length of human pregnancies from conception to birth varies according to a distribution that is approximately Normal with a mean of 266 days and standard deviation of 16 days.
What is the instrument uncertainty? What is the total uncertainty of the next measurement(95% confidence)
Suppose we toss a fair coin 100 times. Fill in the blanks: Use the Normal approximation to find the probability that the sample proportion is
In X-city, 52 % of households have a personal computer. In a random sample of 250 households, what is the probability that fewer than 120 have a PC?
The height in the population of hobbits is distributed normally with mean 100cm and standard deviation 10cm. You know that Bilbo the hobbit's height is below average. What is the probability that Bi
A set of final examination grades in an introductory statistics course was found to be normally distributed with a mean of 73 and a standard deviation of 8.
In a poll to estimate presidential popularity, each person in a random sample of 990 voters was asked to agree with one of the following statements: 1. The president is doing a good job.
Find the probability that the sea urchin will require 4 or more hours to ingest a 5 cm. blade of turtle grass. Find the probability that a sea urchin will require between 2 and 3 hours to ingest a 5 c
Scientists studying a particular species of endangered primate are concerned that the health of the primates is in danger due to habitat loss and malnutrition. Even a slight decrease in average body
Suppose 40% of the population possess a given characteristic. If a random sample of size 300 is drawn from the population, then the probability that 44% or fewer of the sample possess the characteri
The following data comes from the 2011 Behavioral Risk Factor Surveillance System (BRFSS) survey, which is run by the Centers for Disease Control (CDC). This is a joint probability table for the pr
A quality control inspector has drawn a sample of 13 light bulbs from a recent production lot. If the number of defective bulbs is 2 or less, the lot passes inspection. Suppose 20% of the bulbs in
Assuming that other factors are held constant, which of the following would tend to increase the likelihood of rejecting the null hypothesis?
A study has show that a certain injured lion will capture it prey about once in every ten attempts.
The time until recharge for a battery in a laptop computer under common conditions is normally distributed with mean of 275 minutes and a standard deviation of 50 minutes.
The fill volume of an automated filling machine used for filling cans of carbonated beverage is normally distributed with a mean of 12.4 fluid ounces and a standard deviation of 0.1 fluid ounce.
Assuming that the average noise level of hospitals is what it's supposed to be, what is the probability of a sample of 81 hospitals producing an average as high as our sample's (p-value)? Which come