Exam 6: Putting Statistics to Work

Provide an appropriate response. -An environmental group is investigating global warming and is conducting a hypothesis test. The hypotheses are as follows: Null hypothesis: The mean temperature has not changed in recent years Alternative hypothesis: The mean temperature has increased in recent years Do you think that the environmental group would prefer a significance level of 0.05 or 0.01. Why? Do you think that car manufacturers would prefer a significance level of 0.05 or 0.01? Why?

State whether you think the difference between what occurred and what you would expect by chance is statisticallysignificant. -34 of the 220 suicide cases occurred on a Monday.

Find the standard deviation for the given data. Round your answer to one more decimal place than the original data. - 40 20 37 20 17 49 72

Answer the question. -Tell which of the following distributions would have the least variation.

Find the mode(s)for the given sample data. - $96,25,96,13,25,29,56,96$

Use the 68-95-99.7 rule to solve the problem. -Assume that a distribution has a mean of 28 and a standard deviation of 7. What percentage of the values in the distribution do we expect to fall between 21 and 28?

Provide an appropriate response. -The range and standard deviation of the data set below are 35 and 12.47 respectively. $5,24,25,26,40$ If the 26 is replaced with 39, how will this affect the range? How will this affect the standard deviation. Use your answers to explain why the standard deviation is preferable to the range as a measure of variation.

Find the range for the given data. -The manager of an electrical supply store measured the diameters of the rolls of wire in the inventory. The diameters of the rolls (in m)are listed below. 0.519 0.599 0.137 0.341 0.335 0.118

Select the requested distribution. -Which of the distributions is symmetric?

Solve the problem. -Assume that math SAT scores are normally distributed with a mean of 500 and a standard deviation of 100. A score of 560 represents what percentile? Round the percentile to the nearest Tenth.

Identify the distribution as symmetric, left-skewed, or right-skewed. -The diameters of the apples growing on a particular tree

Find the standard score for the given data value. -A data value in the 31st percentile.

The result of a hypothesis is described in terms of the probability of obtaining a particular sample. Use the given contextto formulate the null and alternative hypotheses. Discuss whether the sample provides evidence for rejecting the nullhypothesis. -A company claims that the proportion of defectives among its new DVD players is only $0.01 ( 1 \% )$ . A consumer group believes that the proportion of defectives is higher than this. The consumer group picks a random sample of 200 of the DVD players and finds the proportion of defectives in the sample to be $0.022$ . Assuming that the proportion of defectives for all the company's DVD players is $p = 0.01$ , the probability of selecting a sample in which the proportion of defectives is $0.022$ or more is $0.044$ .

Identify the distribution as symmetric, left-skewed, or right-skewed. -Number of siblings of adults in the U.S.

Solve the problem. Round your answer to two decimal places. -Scores on a test are normally distributed with a mean of 86 and a standard deviation of 3. What is the exam score corresponding to a standard score of -0.95?

Obtain the five-number summary for the given data. -The weights (in pounds)of 18 randomly selected adults are given below. 120 145 187 153 119 138 127 142 179 164 182 202 114 174 130 149 167 174 114 174 130 149 167

Provide an appropriate response. -How does $Q _ { 3 } - Q _ { 2 }$ compare to $Q _ { 2 } - Q _ { 1 }$ for a distribution which is skewed to the right? for a distribution which is skewed to the left? for a uniform distribution? (The three quartiles of a data set from smallest to largest are denoted $\left. \mathrm { Q } _ { 1 } , \mathrm { Q } _ { 2 } , \mathrm { Q } _ { 3 } \right)$ .

Solve the problem. -In a certain country, weights of women are normally distributed with a mean of 138 lb and a standard deviation of 15 lb. What percentage of women in that country weigh more than 120 lb?

Answer the question. -Tell which of the following distributions would have the least variation. 4)

Find the standard deviation for the given data. Round your answer to one more decimal place than the original data. -The numbers below represent the test scores of nine students. $46,81,54,53,27,41,67,33,89$ Find the standard deviation.