BUAL 2650 Final Exam UPDATED QUESTIONS AND CORRECT ANSWERS

BUAL 2650 Final Exam UPDATED
QUESTIONS AND CORRECT ANSWERS
Suppose that a random variable x has a uniform distribution with c = 2 and d =8. Find P(3 <= x <= 5)
- CORRECT ANSWER .333



Find the area under the normal curve when P(Z > -2) - CORRECT ANSWER .9772



Find the area under the normal curve between P(1 < z <2) - CORRECT ANSWER .1359



In a manufacturing process, we are interested in measuring the average length of a certain type of bolt.
Past data indicate that the standard deviation is .25 inches. How many manufactured bolts should be
sampled in order to make us 95 percent confident that the sample mean bolt length is within .02
inches of the true mean bolt length? - CORRECT ANSWER 601



Rejecting a true null hypothesis is called a ________ error. - CORRECT ANSWER Type 1



A recent study conducted by the state government attempts to determine whether the voting public
supports a further increase in cigarette taxes. The opinion poll recently sampled 1,500 voting-age
citizens. 1,020 of the sampled citizens were in favor of an increase in cigarette taxes. The state
government would like to decide if there is enough evidence to establish whether the proportion of
citizens supporting an increase in cigarette taxes is significantly greater than .66. Identify the null
hypothesis. - CORRECT ANSWER p ≤ .66



In testing H0: μ= 23; versus HA: μ > 23 using the critical value rule, when x¯ = 26, s = 6, and n = 20,
what is the value of the test statistic? Assume that the population from which the sample is selected is
normally distributed. - CORRECT ANSWER 2.24



In a manufacturing process, a random sample of 36 manufactured bolts has a mean length of 3 inches
with a standard deviation of .3 inches. What is the 99 percent confidence interval for the true mean
length of the manufactured bolt? - CORRECT ANSWER 2.228 to 3.772



A confidence interval for the population mean is an interval constructed around the ________. -
CORRECT ANSWER sample mean

, When the population is normally distributed, population standard deviation σ is unknown, and the
sample size is n = 15, the confidence interval for the population mean μ is based on the z (normal)
distribution. - CORRECT ANSWER the t distribution



The exact spread of the t distribution depends on the ________. - CORRECT ANSWER
number of degrees of freedom



______ says that if the sample size is sufficiently large, then the sample means are approximately
normally distributed. - CORRECT ANSWER The Central Limit Theorem



The mean of a standard normal distribution is always equal to ________. - CORRECT ANSWER
0



________ values of the standard deviation result in a normal curve that is wider and flatter. -
CORRECT ANSWER larger



The area under the curve of a valid continuous probability distribution must ________. - CORRECT
ANSWER equal 1



A continuous probability distribution having a rectangular shape, where the probability is evenly
distributed over an interval of numbers is a(n) ________ distribution - CORRECT ANSWER
uniform



The specific shape of each normal distribution is determined by its ________ and ________. -
CORRECT ANSWER mean, standard deviation



If the random variable x is normally distributed, ______ percent of all possible observed values of x
will be within three standard deviations of the mean - CORRECT ANSWER 99.73



Which of the following statements is not a property of the normal probability distribution? -
CORRECT ANSWER 95.44 percent of all possible observed values of the random variable x
are within plus or minus three standard deviations of the population mean.



The normal approximation of the binomial distribution is appropriate when - CORRECT ANSWER
np ≥ 5 and n(1 − p) ≥ 5.