Question

If n=50, Std Dev from the mean =2, Tail = 1, what is P and how is it found? What if it is two tailed?

Inversely,

if n = 100, Std Dev from the mean is unknown, tails = 1, and P =.05, what is Std Dev and how is it found? What if it is two tailed?

Answer #1

1)

one tailed

p value = P(Z>2) = 0.0228

excel formula for probability from z score is
=NORMSDIST(-2)

========================

if two tailed,

p value = 2*P(Z>2) = 2 * 0.0228 = 0.0455

2)

one tailed

Z value at 0.05 =
-1.645 (excel formula =NORMSINV(
0.05 ) )

so, Std Dev from the mean = -1.645

-------------

two tailed

p value = 0.05

z value at 0.05/2 = 0.025 = ±
1.960 (excel formula =NORMSINV(
0.05 / 2 ) )

std dev from mean = 1.96

N
Mean
Std. Deviation
Std. Error Mean
AGE
25
35.6800
11.2979
2.2596
If we test H0: μ ≥ 40, can we reject the null
hypothesis? Compare the p-value from the output to the
alpha level to make your decision.
(Hint: This is a one-tailed test; Use the two-tailed
p-value (from the output) divided by 2 to get one-tailed
p-value)
Yes, at both the .01 and .05 levels.
At the .01 level, but not at the .05 level.
At...

H0: u = 735, H1: u > 735
n = 10
mean = 736.5399
Std dev = 18.8971
C = 0.95
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b) Is the null hypothesis rejected or do we fail to reject it?
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550
Population
Summary statistics:
Column
n
Mean
Variance
Std. dev.
Std. err.
Median
Range
Min
Max
Q1
Q3
Books
368
442
32868
181.3
9.451
416.5
920
80
1000
300
600
Summary statistics:
Column
n
Mean
Variance
Std. dev.
Std. err.
Median
Range
Min
Max
Q1
Q3
mean(Sample(Books))
1000
444
1045.1
32.33
1.022
441.4
218.6
353.6
572.1
420.8
465.5
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n
Mean (grams)
STD. Dev(grams)
Mapano Island
24
47.5
2.97
Kinawa Island
30
44.2
2.24
Find the 95% confidence interval for the difference in mean
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A normally distributed risk is described below.
Risk:
Auto losses
Mean:
300,000
Std. Dev.
50,000
What is the probability that losses will be below:
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2
A normally distributed speculative risk is described below.
Risk:
Exchange rate losses
Mean:
50,000
Std. Dev.
100,000
What is the probability that losses will be below:
-50,000
3
A normally distributed risk is described below.
Risk:
Employee injuries
Mean:
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The risk manager is 99.5% certain that losses will be below
3,000,000.
What is...

The mean chicken weight is 5lb, with a std dev of 1 lb. We want
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What is the probability that the sample mean is between 4.9 and
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What is the probability that the combined weight of the
chickens between 490 and 510 lb?
Find the value a, such that the combined weight exceeds a with
probability 95%.
Find the value b, such that the combined weight is below b...

Using a = 0.05, test for a difference in the
means.
group
n
mean sample std dev
1
20
8.3
3.0
2
20
7.2
3.0
ttest u1 = u2 ( VS NE) t= 1.16

Summary Statistics for Number of People in Households
Place
Mean
Median
Std. dev.
IQR
n
Ealing England 1599
4.68
4
2.74
3
85
Bristol RI 1689
5.82
6
2.75
4
72
Nishinomoya Japan 1713
4.99
5
2.51
4
132
Belgrad Serbia 1734
5.41
5
2.62
4
178
Longuenesse France 1778
5.02
5
2.51
4
66
Vaudreuil-Soulanges, Quebec 1851
6.63
7
2.75
4
97
California students, 2008-2009
3.99
4
1.55
2
272
Australian Students, 2008
4.46
4
1.25
1
569
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1. Which of the following statements is correct?
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b.
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d.
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