Question

The home run percentage is the number of home runs per 100 times at bat. A random sample of 43 professional baseball players gave the following data for home run percentages.

1.6 | 2.4 | 1.2 | 6.6 | 2.3 | 0.0 | 1.8 | 2.5 | 6.5 | 1.8 |

2.7 | 2.0 | 1.9 | 1.3 | 2.7 | 1.7 | 1.3 | 2.1 | 2.8 | 1.4 |

3.8 | 2.1 | 3.4 | 1.3 | 1.5 | 2.9 | 2.6 | 0.0 | 4.1 | 2.9 |

1.9 | 2.4 | 0.0 | 1.8 | 3.1 | 3.8 | 3.2 | 1.6 | 4.2 | 0.0 |

1.2 | 1.8 | 2.4 |

(a) Use a calculator with mean and standard deviation keys to
find x and *s*. (Round your answers to two decimal
places.)

x = | |

s = |

(b) Compute a 90% confidence interval for the population mean μ
of home run percentages for all professional baseball players.
*Hint:* If you use the Student's *t* distribution
table, be sure to use the closest *d.f.* that is
*smaller*. (Round your answers to two decimal places.

lower limit

upper limit

(c) Compute a 99% confidence interval for the population mean μ of home run percentages for all professional baseball players. (Round your answers to two decimal places.)

lower limit

upper limit

Answer #1

(a) From the given data

= 2.29

s = 1.40

_____________

(b) 90% CI

t critical for df = n - 1 = 42 for = 0.1 is 1.68

The Lower Limit = - tcritical * s / sqrt(n) = 2.29 - 1.68 * 1.4 / sqrt(43) = 1.93

The Upper Limit = + tcritical * s / sqrt(n) = 2.29 + 1.68 * 1.4 / sqrt(43) = 2.65

**The 90% CI is (1.93, 2.65)**

**____________**

(b) 99% CI

t critical for df = n - 1 = 42 for = 0.01 is 2.698

The Lower Limit = - tcritical * s / sqrt(n) = 2.29 - 2.698 * 1.4 / sqrt(43) = 1.71

The Upper Limit = + tcritical * s / sqrt(n) = 2.29 + 2.698 * 1.4 / sqrt(43) = 2.87

**The 99% CI is (1.71, 2.87)**

**____________**

The home run percentage is the number of home runs per 100 times
at bat. A random sample of 43 professional baseball players gave
the following data for home run percentages.
1.6
2.4
1.2
6.6
2.3
0.0
1.8
2.5
6.5
1.8
2.7
2.0
1.9
1.3
2.7
1.7
1.3
2.1
2.8
1.4
3.8
2.1
3.4
1.3
1.5
2.9
2.6
0.0
4.1
2.9
1.9
2.4
0.0
1.8
3.1
3.8
3.2
1.6
4.2
0.0
1.2
1.8
2.4
(a) Use a calculator with mean...

The home run percentage is the number of home runs per 100 times
at bat. A random sample of 43 professional baseball players gave
the following data for home run percentages.
1.6
2.4
1.2
6.6
2.3
0.0
1.8
2.5
6.5
1.8
2.7
2.0
1.9
1.3
2.7
1.7
1.3
2.1
2.8
1.4
3.8
2.1
3.4
1.3
1.5
2.9
2.6
0.0
4.1
2.9
1.9
2.4
0.0
1.8
3.1
3.8
3.2
1.6
4.2
0.0
1.2
1.8
2.4
(a) Use a calculator with mean...

The home run percentage is the number of home runs per 100 times
at bat. A random sample of 43 professional baseball players gave
the following data for home run percentages.
1.6
2.4
1.2
6.6
2.3
0.0
1.8
2.5
6.5
1.8
2.7
2.0
1.9
1.3
2.7
1.7
1.3
2.1
2.8
1.4
3.8
2.1
3.4
1.3
1.5
2.9
2.6
0.0
4.1
2.9
1.9
2.4
0.0
1.8
3.1
3.8
3.2
1.6
4.2
0.0
1.2
1.8
2.4
(a) Use a calculator with mean...

The home run percentage is the number of home runs per 100 times
at bat. A random sample of 43 professional baseball players gave
the following data for home run percentages.
1.6
2.4
1.2
6.6
2.3
0.0
1.8
2.5
6.5
1.8
2.7
2.0
1.9
1.3
2.7
1.7
1.3
2.1
2.8
1.4
3.8
2.1
3.4
1.3
1.5
2.9
2.6
0.0
4.1
2.9
1.9
2.4
0.0
1.8
3.1
3.8
3.2
1.6
4.2
0.0
1.2
1.8
2.4
(a) Compute a 90% confidence interval...

Provided in the date below a set of restoration times for 35
failed power transformers. The data were collected for recent
transformer failures by a fairly novice work crew. a. What is a 90%
confidence interval for mean restoration time? b. What is a 99%
confidence interval for mean restoration time? c. If the industry
standard for such a restoration is 2.7 hours, discuss how well the
work crew in this analysis performed.
2.2
1.7
2.4
2.5
2.9
4.4
5.1...

these are percentages of annual sales growth and net sales
attributed to loyalty card usage at 74 noodels and company
restaurant
Store
Growth%
Loyalty%
Store
Growth%
Loyalty%
1
-7.7
0.7
38
7.1
1.7
2
-7.5
2.0
39
7.3
1.2
3
-6.4
1.3
40
7.7
1.7
4
-4.4
1.4
41
7.8
2.4
5
-4.1
2.0
42
8.3
2.1
6
-2.0
2.5
43 ...

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