Select five cards without replacement from a standard deck of 52, and let X be the
number of black cards you draw. What is the expected value of the given random
variable X ?
0.5
1.8
2.5
3.2
26
Y , 2 Y , 3 Y form a set of S . Given that ( | 1 ) 0.4 P X Y = , ( | 2 ) 0.5 P X Y = ,
( | 3 ) 0.7 P X Y = , ( 1 ) 0.7 P Y = , and ( 2 ) 0.1 P Y = , then what is ( 1 | ) P Y X ?
0.098
0.1064
0.2979
0.4043
0.5957
The following histogram shows the distribution of the difference between “ideal” and
actual heights for 120 students. What is the approximate shape of the distribution?
Nearly symmetric.
Skewed to the right.
Skewed to the left
Has two peaks.
The proportion of people who enter the store will buy something is 57%. A random
sample of 802 people who go to the store is taken. What is the sampling distribution of
the sample proportion?
N(0.2484, 0.01762 )
N(0.2484, 0.02592 )
N(0.57, 0.02592 )
N(0.57, 0.01762 )
For a random sample of 9 chocolate bars, the average weight is 100g, and the sample
standard deviation is 5. What is the standard error of the sample mean?
1.667
2.778
0.557
0.745
A local health center noted that in a sample of 400 patients 80 were referred to them by
the local hospital. What size sample would be required to estimate the proportion of
hospital referrals with a margin of error of 0.04 or less at 95% confidence?
(三) Determine the p-value; and at 95% confidence, test the above hypotheses.
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