bstat

A random sample of size 100 is taken from a population described by the proportion p = 0.60. What are the expected value and the standard error for the sampling distribution of the sample proportion?

0.6000 and 0.049

The time to complete the construction of a soapbox derby car is normally distributed with a mean of three hours and a standard deviation of one hour. Find the probability that it would take exactly 3.7 hours to construct a soapbox derby car.

0000000000 the standard deviation has to be bigger than 5

The time to complete the construction of a soapbox derby car is normally distributed with a mean of three hours and a standard deviation of one hour. Find the probability that it would take more than five hours to construct a soapbox derby car.

IT IS NOT 0.9772 YOU HAVE TO SUBTRACT FROM SINCE IT IS ONE CYCLE SO IT IS 0.0228

It is known that the length of a certain product X is normally distributed with μ = 36 inches. How is the probability P(X > 32) related to P(X < 32)?

P(X>32)is greater than P(x<32)

If X has a normal distribution with µ = 100 and σ = 5, then the probability P(90 ≤ X ≤ 95) can be expressed in terms of a standard normal variable Z as ______.

P(−2 ≤ Z ≤ −1)

Which of the following is the necessary condition for creating confidence intervals for the population mean?

the normality of the estimator

A random sample of size 100 is taken from a population described by the proportion p = 0.60. The probability that the sample proportion is less than 0.55 is ______.

1537

For a given confidence level and sample size, which of the following is true in the interval estimation of the population mean when σ is known?

If the population standard deviation is greater, the interval is wider.

Let X be normally distributed with mean μ and standard deviation σ > 0. Which of the following is false about the z value corresponding to a given xvalue?

Let X be normally distributed with mean μ and standard deviation σ > 0. Which of the following is false about the z value corresponding to a given xvalue?

Which of the following can be represented by a discrete random variable?

The number of defective light bulbs in a sample of five

Which of the following can be represented by a discrete random variable?

The number of obtained spots when rolling a six-sided die

Which of the following is NOT a characteristic of the probability mass function of a discrete random variable X?

The probability P(X ≤ x) for every possible value x is equal to 1.

It is known that the length of a certain product X is normally distributed with μ = 20 inches. How is the probability P(X > 16) related to P(X < 16)?

being P(X>16) is greater than P(X<16)

Super Bowl XLVI was played between the New York Giants and the New England Patriots in Indianapolis. Due to a decade-long rivalry between the Patriots and the city's own team, the Colts, most Indianapolis residents were rooting heartily for the Giants. Suppose that 90% of Indianapolis residents wanted the Giants to beat the Patriots.What is the probability that from a sample of 40 Indianapolis residents, fewer than 95% were rooting for the Giants in Super Bowl XLVI?

cannot be determined

for a given confidence level and sample size, which of the following is true in the interval estimation when σ is known?

if the population standard deviation the interval is wider

The central limit theorem states that, for any distribution, as n gets larger, the sampling distribution of the sample mean ______.

is closer to a normal distribution

Find the probability P(−1.96 ≤ Z ≤ 1.96).

it is .9500 the z score of the first subtracted from z score of 2nd

A sample of a given size is used to construct a 95% confidence interval for the population mean with a known population standard deviation. If a bigger sample had been used instead, then the 95% confidence interval would have been _______ and the probability of making an error would have been ________.

narrower/ unchanged

which of the following is the necessary condition for creating confidence intervals for the population mean.

normality of the estimator

Using the central limit theorem, applied to the sampling distribution of the sample proportion, what conditions must be met?

np≥5np≥5 and n(1−p)≥5n(1⁢−p⁢ ) ≥ 5

Suppose the life of a particular brand of laptop battery is normally distributed with a mean of 8 hours and a standard deviation of 0.6 hours. What is the probability that the battery will last more than 9 hours before running out of power?

the answer is 0.0478. it is not 0.9525 u have to subtract 1 from this. to find 0.9525. 1.66 then go to z table

You are planning a May camping trip to Denali National Park in Alaska and want to make sure your sleeping bag is warm enough. The average low temperature in the park for May follows a normal distribution with a mean of 32°F and a standard deviation of 8°F. An inexpensive bag you are considering advertises to be good for temperatures down to 38°F. What is the probability that the bag will not be warm enough?

the answer is 0.7734. not .75 .75 is used for the z score table

According to a report in USA Today, more and more parents are helping their young adult children get homes. Suppose eight persons in a random sample of 40 young adults who recently purchased a home in Kentucky received help from their parents. You have been asked to construct a 95% confidence interval for the population proportion of all young adults in Kentucky who received help from their parents. If a 99% confidence interval is constructed instead of a 95% confidence interval for the population proportion, then __________.

the resulting margin of error will increase and the risk of reporting an incorrect interval will decrease

An investment consultant tells her client that the probability of making a positive return with her suggested portfolio is 0.90. What is the risk, measured by standard deviation that this investment manager has assumed in her calculation if it is known that returns from her suggested portfolio are normally distributed with a mean of 6%?

4.69%

Sarah's portfolio has an expected annual return at 8%, with an annual standard deviation at 12%. If her investment returns are normally distributed, then in any given year Sarah has an approximate ______.

50% chance that actual return will be greater than 8%

What is zα/2zα/2 for a 90% confidence interval of the population mean?

1.645

Suppose taxi fares from Logan Airport to downtown Boston is known to be normally distributed and a sample of seven taxi fares produces a mean fare of $22.31 and a 95% confidence interval of [$20.5051, $24.2091]. Which of the following statements is a valid explanation of the confidence interval.

We are 95% confident that the average taxi fare between Logan Airport and downtown Boston will fall between $20.51 and $24.21.

For any normally distributed random variable with mean μ and standard deviation σ, the proportion of the observations that fall outside the interval [μ − σ, μ + σ] is the closest to ______.

0.3174

The probability that a normal random variable is less than its mean is ______.

0.5

What is zα/2zα/2 for a 90% confidence interval of the population mean?

1.645!!!!!!!!!!!!

A nursery sells trees of different types and heights. These trees average 60 inches in height with a standard deviation of 16 inches. Suppose that 75 pine trees are sold for planting at City Hall. What is the standard deviation for the sample mean?

1.85 just the smaller one in multiple choice

If a population is known to be normally distributed, what can be said of the sampling distribution of the sample mean drawn from this population?

For any sample size n, the sampling distribution of the sample mean is normally distributed.

The ages of MBA students at a university are normally distributed with a known population variance of 10.24. Suppose you are asked to construct a 95% confidence interval for the population mean age if the mean of a sample of 36 students is 26.5 years. If a 99% confidence interval is constructed instead of a 95% confidence interval for the population mean, then __________.

the resulting margin of error will increase and the risk of reporting an incorrect interval will decrease

Find the probability P(−1.96 ≤ Z ≤ 0).

the z of -1.96 is 0.0250 and the Z of 0 is 0.5000 then just subtract to get the inbetween.