Mean and Standard Deviation
AP Statistics · Flashcards · Application
AP STATISTICS · FLASHCARDS
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QUESTION
Calculate the mean of a random variable
X
X
X
with
E
(
X
)
=
5
E(X) = 5
E
(
X
)
=
5
after transformation
Y
=
3
X
+
2
Y = 3X + 2
Y
=
3
X
+
2
.
QUESTION
Find the variance of a random variable
X
X
X
with
V
a
r
(
X
)
=
9
Var(X)=9
V
a
r
(
X
)
=
9
after
Y
=
2
X
−
3
Y=2X-3
Y
=
2
X
−
3
.
QUESTION
Calculate the variance for
P
(
X
=
1
)
=
0.4
P(X=1)=0.4
P
(
X
=
1
)
=
0.4
,
P
(
X
=
2
)
=
0.6
P(X=2)=0.6
P
(
X
=
2
)
=
0.6
. Mean is
1.6
1.6
1.6
.
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ANSWER
Variance is
0.24
0.24
0.24
. Sum
(
x
i
−
1.6
)
2
×
p
i
(x_i - 1.6)^2 \times p_i
(
x
i
−
1.6
)
2
×
p
i
for each value.
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