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Unformatted text preview: Exam #2 Stat 251
Winter 2006 Namt Solve the problem. 2. ‘ (i) We know that the sam devration. The center ' g center wants to determine the proportion of business students who
ave personal computers (PCs) at home. If the proportion diff
2: 2 . <o= .445 ers from 35%, then the lab will
odify a proposed enlargement of its facilities. Suppose a hyp othesis test is conducted and the test
, statistic is 2.6. Find the p—value for a two—tailed test of hypoth ?“Vﬂ\=(Z.>2il0)= 7.>.‘l463 esis.
.S‘.“\’l‘>2> ’ .0047 * 1 = .0044
B) .4906 n = (7, xiii)ng ml : 3.2.17, ’4 7:172
(5 2. B) 161 C) 3 @3
n: L} 000 5) Many people think that a national lobby s successful fight a gainst gun control legislation IS
7:) _ )160 gbﬁﬁﬂectmg the Will of a minority of Americans A random sample of 4,000 Citizens yielded 2 250 who
) #356 = are in favor of gun control legislation. Estimate the true proportion of all Americans who are in
favor of gun control legislation usin a 90% confidence i terval.
2.42407, :Wis «Stole I [.mqg,§(.smsvr.+316)i = Bezel 0,011”!
: 4 2,1 5 b B) .4375 2 .4048 D) .5625 1 .4048 .5625 t .0129
« J 31
Kg“) @4375 2 .0129 We have created a 99% confidence interval for p. with the result (11, 16). What conclusion will we 6)
makeifwetestH0:u=21vs.Ha:uz21at0L=.01? Hoax/(22‘ \%‘0=13.€=§
A) Fail to reject H0. ‘H‘A imkll
@Reject H0 in favor of Ha. u g ' o ‘ Zia/:44 ‘l' = 2.5?)
C) Accept H0 in favor of Ha. D) We cannot tell what our decision will be with the information given. A—1 \\ V0 2\ m“:
‘i 3)C. N B A randomly selected ball bearing has a diameter greater than 3.1 millimeters? ZS LlS = Li’.5"%.l Jﬁ 4'4 4.5—2.5 : 2. ‘0'7
A) 0.6889 B) 1.5 C) 0.4429 .7
h ‘ 250 8) A univerSity IS conSIdering a change in the way students pay for their education Presently, the
X 1 H I \ students pay $16 per credit hour The univerSity is contemplating charging each student a set fee of per student per quarter using a 99% confidence interval. ii.\:2.ecb(%) = \Hli .515 A) 14.1 1 .024 B) 14.1 1 .016 C) 14.1 1 .247 4.1 t .375 @5811 ppose we wish to test H0: p. = 34 vs. Ha: u < 34 Which of the following possible sample results gies the most evidence to support Ha (i.e., reject H0)? Assume n=30. x=32,s=6 B)x=33,s=8:‘/\ @=39,s=2
/ :—\~%73 jﬁglyf ;~ la . W5 .' 6 “7 a ' _‘
~10) The amount of corn chips dispensed into a 15—ounce bag by the dispensing machine has been C)x=31,s=42;(\ 7 1' l5 identified at possessmg a normal distribution with a mean of 15 5 ounces and a standard deViation
O : O . g) of 0 3 ounce Suppose 100 bags of chips were randomly selected from this dispensmg machine
h = ‘00 Find the probability that the sample mean weight of these 100 bags exceeded 15 6 ounces
2. _ " \5'S—lglb w ‘32) ‘4;
MX ‘093’ thew“ 4.93 as 0" “MK. 1 5 .s x “z . 7) 6 D7; A) .1915 @pproximately 0 C) .3085 D) .6915
/ ‘
\0 site, the wind speeds averaged Q = 14.2 mph, with a standard deviation of s = 3.5 mph. To : 5 determine whether the site meets the organization's requirements, consider the test,
Ho ",Ll, T '5 H041 = 15 vs. Ha: p. > 15, where it is the true mean wind speed at the site and a = .05. Fill in the
HA ' 11> l 5 blanks. "A Type I error in the context of this problem is to conclude that the true mean wind speed
0" ; \ 08 at the site 15 mph when it actually 15 mph."
#exceeds; exceeds —B)equals; equals 'C) equals; exceeds xceeds; equals 7)D @3832 seconds B) 536.8 seconds @3613 seconds D) 558.7 seconds
TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. Answer the question True or False. ’ 15) As the sample size taken gets larger, the standard error of the sampling dxstrrbutron of the sample ) T
mean gets larger as well.
@ The smaller the p—value in a test of hypothesis, the more the results dlsagree W1th the null W l:
th 7 ’
hypo e519 T312 yr 21‘ . rpret the
F : ‘Ob (segult in the context of the problem (1 sentence). 5
___,_ 7 ‘ v _ . 2 . D
we 9’ z= .smfbs‘ ; 1332. \ 4
2‘ ‘ w M. /__.. = LDD— J1
61" .lt7 WEE'5’) vows "m
l’ we tpam TD ref“? Ho m tint
exqmﬁmme Mex <>«—.\O. L1?)  Ther ﬁfmgﬁgjdgym euxvlmm MM X4 dee—WCts 06mch MQV‘FCHW ~WWCW1 <25! mutomm W, Wt \n W ...
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