Stats 1222 Exam 2
A woman buys 20 one-dollar lottery tickets per month. The probability of any ticket being a winning ticket is 0.10 or 10%. Which of the following shows the correct EXCEL formula to find the probability that in any one month, at least three of the tickers that the woman buys are winning tickets?
=1 - BINOM.DIST(2, 20, 0.10, TRUE)
Assume that children's IQs (Age 6-12) follow a normal distribution with mean 100 and standard deviation of 12. Find the probability that a randomly selected child has IQ above 115.
=1-NORM.DIST(115, 100, 12, TRUE)
An inspection of 160 parts made from two production lines at a factory yields the following table. A part is randomly selected from these 160 parts. Line 1 Line 2. total good 65. 82. 147 defective. 5. 8. 13 total. 70. 90. 160 The probability that this part is good is about ________.
=147/160
At Hopewell Electronics, all 140 employees were asked about their political affiliations: Democrat, Republican or Independent. The employees were grouped by type of work, as executives or production workers. The results with row and column totals are shown in the following table. Suppose an employee is selected at random from the 140 Hopewell employees. The probability that this employee is a Republican is about ________________
=55/140
In a survey of 1000 people, 700 people said that they voted in the last presidential election. Let p denote the proportion of all people who voted. Which of the following calculates the point estimate for p and also the critical value for the 90% confidence interval for p?
=700/1000 and =NORM.INV(1-0.10/2,0,1)
You are taking a multiple-choice quiz that consists of twenty questions. Each question had six possible answers, only one of which is correct. To complete the quiz, you randomly guess the answer to each question. Which of the following shows the correct EXCEL formula to compute the probability of guessing less than five answers correctly.
=BINOM.DIST(4, 20, 1/6, TRUE)
Last Wednesday, a random sample of 16 students was surveyed to find how long it takes to walk from the Fretwell building to the College of Education building. The survey team found a sample mean of 10 minutes with a standard deviation of 1.6 minutes. Assuming walking times from Fretwell to the College of Education are normally distributed, which of the following calculates the margin of error (EBM) for the 89% confidence interval for the population mean of walking times?
=CONFIDENCE.T(0.11, 1.6, 16)
The amount of time spent by individuals completing Form 1040 Schedule U of U. S. tax returns is normally distributed with mean 73 minutes and standard deviation 12 minutes. Suppose 10 randomly selected people are timed completing Schedule U. Find the probability that the mean time to complete the form will be between 70 and 75 minutes.
=NORM.DIST(75, 73, 12/SQRT(10), TRUE) - NORM.DIST(70, 73, 12/SQRT(10), TRUE)
Consider the three normally distributed random variables A, B, and C, pictured below. Which of the following is a true statement?
All 3 have the same mean, and A has the smallest standard deviation.
In a survey of 1000 people, 700 people said that they voted in the last presidential election. Let p denote the proportion of all people who voted. Which of the following actions would result in a confidence interval narrower than the 95% confidence interval computed from this sample?
Computing a 80% confidence interval rather than a 95% confidence interval
In a random sample of 32 criminals convicted of a certain crime, it was determined that the mean length of sentencing was 57 months, with a standard deviation of 12 months. A district attorney calculated the 95% confidence interval for the mean length of sentencing for this crime and he got 52.7 for the lower bound and 61.3 for the upper bound. Interpret the interval.
We can be 95% confident that the mean length of sentencing for the crime is between 52.7 and 61.3 months.
A manufacturer claims that the mean weight of its ice cream cartons is 10ounces with a standard deviation of 0.6 ounce. Assuming 36 cartons are selected. Let x bar represent the mean sales price of the sample. Find the mean and standard deviation of x bar, i.e., mean x bar and std. dev. x bar :
mean x bar: 10 std dev x bar: 0.6/sqrt(36)
A survey in a community states that 480 out of 1200 people smoke on a regular basis. Using the information from this survey, a researcher wishes to estimate the required sample size. He wants to be 80% confident and wants the sample proportion to be within 2.5% of the population proportion. Which of the following is correct?
p' = 480/1200; q' = 1 - 480/1200; EBP = 0.025
Which of the following random variables is continuous?
the weight of a chicken
