tugas statel 2
TRANSCRIPT
7/24/2019 TUGAS STATEL 2
http://slidepdf.com/reader/full/tugas-statel-2 1/2
8.24 If a certain machine makes electrical resistors
having a mean resistance of 40 ohms and a standard
deviation of 2 ohms, what is the probability that a
random sample of 36 of these resistors will have a combined
resistance of more than 145 ohms!
8.25 "he average life of a bread#making machine is $
years, with a standard deviation of 1 year% &ss'ming
that the lives of these machines follow appro(imately
a normal distrib'tion, find
)a* the probability that the mean life of a random sample
of + s'ch machines falls between 6%4 and $%2
years
)b* the val'e of x to the right of which 15- of the
means comp'ted from random samples of si.e +
wo'ld fall%
8.27 In a chemical process, the amo'nt of a certain
type of imp'rity in the o'tp't is diffic'lt to control
and is th's a random variable% /pec'lation is that the
pop'lation mean amo'nt of the imp'rity is 0%20 gram
per gram of o'tp't% It is known that the standard
deviation is 0%1 gram per gram% &n e(periment is cond'cted
to gain more insight regarding the spec'lation
that μ 0.2% "he process is r'n on a lab scale 50
times and the sample average ̄x t'rns o't to be 0%23
gram per gram% omment on the spec'lation that the
mean amo'nt of imp'rity is 0%20 gram per gram% ake
'se of the entral imit "heorem in yo'r work%
8.28 & random sample of si.e 25 is taken from a normal
pop'lation having a mean of 0 and a standard
deviation of 5% & second random sample of si.e 36
is taken from a different normal pop'lation having a
mean of $5 and a standard deviation of 3% ind the
probability that the sample mean comp'ted from the
25 meas'rements will e(ceed the sample mean comp'ted
from the 36 meas'rements by at least 3%4 b't
less than 5%+% &ss'me the difference of the means to
be meas'red to the nearest tenth%
8.29 "he distrib'tion of heights of a certain breed of
terrier has a mean of $2 centimeters and a standard deviation
of 10 centimeters, whereas the distrib'tion of
heights of a certain breed of poodle has a mean of 2
centimeters with a standard deviation of 5 centimeters%
&ss'ming that the sample means can be meas'red to
any degree of acc'racy, find the probability that the
sample mean for a random sample of heights of 64 terriers
e(ceeds the sample mean for a random sample of
heights of 100 poodles by at most 44%2 centimeters%
8.30 "he mean score for freshmen on an aptit'de test
at a certain college is 540, with a standard deviation of
50% &ss'me the means to be meas'red to any degree
of acc'racy% hat is the probability that two gro'ps
selected at random, consisting of 32 and 50 st'dents,
respectively, will differ in their mean scores by
)a* more than 20 points!
)b* an amo'nt between 5 and 10 points!
%24 ika mesin tertent' memb'at resistor listrik
memiliki ketahanan rata#rata 40 ohm dan standar
deviasi 2 ohm, apa adalah probabilitas bahwa
sampel acak dari 36 dari resistor ini akan telah gab'ngan
resistensi dari lebih dari 145 ohm!
,25 7ehid'pan rata#rata mesin pemb'atan roti adalah $
tah'n, dengan standar deviasi dari 1 tah'n% 8engan as'msi
bahwa kehid'pan mesin ini mengik'ti sekitar
distrib'si normal, menem'kan
)a* probabilitas bahwa kehid'pan mean sampel acak
dari + mesin terseb't 9at'h antara 6,4 dan $,2
tah'n
)b* nilai ( ke kanan dari yang 15- dari
berarti dihit'ng dari sampel acak 'k'ran +
akan 9at'h%
%2$ 8alam proses kimia, 9'mlah tertent'
9enis pengotor dalam o'tp't s'lit dikendalikan
dan dengan demikian mer'pakan variabel acak% /pek'lasi adalah bahwa
pop'lasi 9'mlah rata#rata dari kecemaran adalah 0,20 gram
per gram o'tp't% :al ini diketah'i bahwa standar
deviasi adalah 0,1 gram per gram% /eb'ah percobaan dilak'kan
'nt'k mendapatkan wawasan lebih mengenai spek'lasi
bahwa ; 0,2% <roses ini di9alankan pada skala laboratori'm 50
kali dan rata#rata = sampel ternyata men9adi 0,23
gram per gram% engomentari spek'lasi bahwa
berarti 9'mlah pengotor adalah 0,20 gram per gram% emb'at
mengg'nakan dari entral "eorema imit dalam peker9aan &nda%
%2 /eb'ah sampel acak dengan 'k'ran 25 diambil dari normal
pop'lasi memiliki rata#rata 0 dan standar
deviasi 5% /eb'ah sampel acak ked'a 'k'ran 36
diambil dari pop'lasi normal yang berbeda memiliki
berarti dari $5 dan deviasi standar 3% ari
probabilitas bahwa sampel rata2 dihit'ng dari
25 peng'k'ran akan melebihi sampel rata2 dihit'ng
dari 36 peng'k'ran oleh setidaknya 3,4 tapi
k'rang dari 5,+% &s'msikan perbedaan sarana 'nt'k
di'k'r 'nt'k kesep'l'h terdekat%
%2+ 8istrib'si tinggi dari 9enis tertent'
terrier memiliki rata#rata $2 cm dan standar deviasi
dari 10 cm, sedangkan distrib'si
ketinggian dari 9enis tertent' p'del memiliki rata#rata 2
sentimeter dengan standar deviasi dari 5 sentimeter%
8engan as'msi bahwa sampel berarti dapat di'k'r 'nt'k
setiap tingkat ak'rasi, menem'kan probabilitas bahwa
sampel berarti 'nt'k sampel acak dari ketinggian 64 terrier
melebihi sampel berarti 'nt'k sampel acak dari
ketinggian 100 p'del oleh paling 44,2 sentimeter%
%30 ean skor 'nt'k mahasiswa bar' pada tes bakat
di seb'ah perg'r'an tinggi tertent' 540, dengan deviasi standar
50% &s'msikan sarana yang akan di'k'r 'nt'k tingkat apap'n
ak'rasi% >erapa probabilitas bahwa d'a kelompok
dipilih secara acak, yang terdiri dari 32 dan 50 siswa,masing#masing, akan berbeda dalam nilai rata#rata mereka oleh
)a* lebih dari 20 poin!