MATH 227 STATISTICS FINAL EXAM - West Los Angeles College

For problems 85 through 90, consider the following situation - A coin is tossed 10 times.
Suppose that the coin is not fair, and that for each toss of the coin, the probability of getting
a HEAD is 0.6. Let X = the number of heads observed in the 10 tosses.
85. Is the random variable X discrete or continuous
a) discrete b) continuous
86. What possible values does X take on
a) 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
b) 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
c) All Real numbers in the interval [0,10]
d) .6 or .4 only
87. What type of distribution does the random variable X have
a) binomial b) uniform c) normal d) a and b e) b and c
88. Find P( X = 5 )
a) .367 b).201 c) 0 d) 1 e) 0.6
89. Find the mean of the random variable X. Show the best formula that you should use.
a) µ npq , so µ = 2. 4
x
=
b) µ
x
= np , so µ
x
= 6. 0
c) µ
x
= ∑ xp(x)
, so µ
x
= 2. 4
d) µ
x
= ∑ xp(x)
, so µ
x
= 6. 0
e) a and c are both correct
x
90. Find the standard deviation of the random variable X. Show the formula that you used.
a) σ = np( 1−
p)
= 1. 55
x
b) σ = np( 1−
p)
= 2. 4
x
∑ 2
( x − x)
c) s = = 5.5
n −1
d) none of these
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