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Unformatted text preview: Quiz #2 Stat 251 __ 5/6 Wilma Name ——u——‘ MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. Solve the problem. 1) The amount of corn chips dispensed into a 15—ounce bag by the dispensing machine has been
identified at possessing a normal distribution with a mean of 15.5 ounces and a standard deviation
of 0.3 ounce. Suppose 100 bags of chips were randomly selected from this dispensing machine.
Find the probability that the sample mean weight of these 100 bags exceeded 15.6, ounces. A) .6915 \g M B) .1915 C) .3085 .approximately 0
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5—)) «r/ﬁ' 005 2) The tread life of a particular brand of tire is a random variable best described by a normal
distribution with a mean of 60,000 miles and a standard deviation of 1700 miles. What warranty should the company use if they want 96% of the tires to outlast the warranty? ,
A) 58,300 miles ‘3, 7,025 miles C) 61,700 miles @975 miles Z: ) 715 V " l ' moo
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"Ll/u. ‘ (01,47 5 = K 3) Suppose that repeated samples were selected from a population and the sample variance was
calculated for each. The distribution of these sample variances would be called the A) sampling distribution of ; ‘tandard error
@ampling distribution of 52 D) mean of the sampling distribution 4) Find a value of the standard normal random variable 2, called 20, such that P(—zo s z s 20) = 0.98. @353 B) 0.99 C) 1.96 D) 1.645 V7.04?) ”3H4 2.33 Al 1) SHORT ANSWER. Solve the problem 9) A new drug has been synthesized that is designed to reduce a person's blood pressure. 9) O I 1% (01+
Nineteen randomly selected hypertensive patients receive the new drug. Suppose the WW a \ probability that a hypertensive patient's blood pressure drops if he or she is untreated is
vm 0.8. Then what is the probability of observing~17 or more blood pressure drops in a random sample of 19 treated patients if the new drug is in fact ineffective in reducing blood
pressure? to“ Wm?) WM VW (IA—5‘ (0'39”(0 a)” = :0 M
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‘ l rm —~ ( {2VWVJJ'4M = (LOWt 0‘00 10) It has been stated that 0.1 of the general population donate their time and energy to 10) \ \ D working on community projects. Suppose 15 people have been randomly sampled from a
community and asked if they donated their time and energy to community projects. Let x
be the number of them that do donate their time and energy to community projects. Find
the probability that more than five of the 1 do donate eir time and energy to community projects. ('9 7 (b,”l,l0( lift} ,‘15 Nil“;
906%) ' ’ ' ' ' {w VS‘G
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 Fall '06
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