Actuaries use various parameters when evaluating the cost of a life insurance policy. The variance of the life spans of a population is one of the parameters used for the evaluation. Each year, the actuaries at a particular insurance company randomly sample 20 people who died during the year (with the samples chosen independently from year to year) to see whether the variance of life spans has changed. The life span data from this year and from last year are summarized below. Current Last Year Year X 1 = 76.1 x, = 76.4 s = 62.41 s3= 144 (The first row gives the sample means and the second row gives the sample variances.) Assume that life spans are approximately normally distributed for each of the populations of people who died this year and people who died last year. Can we conclude, at the 0.05 significance level, that the variance of the life span for the current year, o, differs from the variance of the life span for last year, o,

Calculus For The Life Sciences
2nd Edition
ISBN:9780321964038
Author:GREENWELL, Raymond N., RITCHEY, Nathan P., Lial, Margaret L.
Publisher:GREENWELL, Raymond N., RITCHEY, Nathan P., Lial, Margaret L.
Chapter13: Probability And Calculus
Section13.2: Expected Value And Variance Of Continuous Random Variables
Problem 10E
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Actuaries use various parameters when evaluating the cost of a life insurance policy. The variance of the life spans of a population is one of the
parameters used for the evaluation. Each year, the actuaries at a particular insurance company randomly sample 20 people who died during
the year (with the samples chosen independently from year to year) to see whether the variance of life spans has changed. The life span data
from this year and from last year are summarized below.
Current
Last Year
Year
x, = 76.1
*2
= 76.4
= 62.41 s = 144
S
(The first row gives the sample means and the second row gives the sample variances.)
Assume that life spans are approximately normally distributed for each of the populations of people who died this year and people who died
last year. Can we conclude, at the 0.05 significance level, that the variance of the life span for the current year, o´, differs from the variance of
the life span for last year,
Transcribed Image Text:Actuaries use various parameters when evaluating the cost of a life insurance policy. The variance of the life spans of a population is one of the parameters used for the evaluation. Each year, the actuaries at a particular insurance company randomly sample 20 people who died during the year (with the samples chosen independently from year to year) to see whether the variance of life spans has changed. The life span data from this year and from last year are summarized below. Current Last Year Year x, = 76.1 *2 = 76.4 = 62.41 s = 144 S (The first row gives the sample means and the second row gives the sample variances.) Assume that life spans are approximately normally distributed for each of the populations of people who died this year and people who died last year. Can we conclude, at the 0.05 significance level, that the variance of the life span for the current year, o´, differs from the variance of the life span for last year,
(a) State the null hypothesis H, and the alternative hypothesis H .
H :0
H : 0
(b) Determine the type of test statistic to use.
|(Choose one) ▼
(c) Find the value of the test statistic. (Round to three or more decimal places.)
(d) Find the p-value. (Round to three or more decimal places.)
(e) Can we conclude that the variance of the life span for the current year differs
from the variance of the life span for last year?
O Yes ONo
Transcribed Image Text:(a) State the null hypothesis H, and the alternative hypothesis H . H :0 H : 0 (b) Determine the type of test statistic to use. |(Choose one) ▼ (c) Find the value of the test statistic. (Round to three or more decimal places.) (d) Find the p-value. (Round to three or more decimal places.) (e) Can we conclude that the variance of the life span for the current year differs from the variance of the life span for last year? O Yes ONo
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ISBN:
9780321964038
Author:
GREENWELL, Raymond N., RITCHEY, Nathan P., Lial, Margaret L.
Publisher:
Pearson Addison Wesley,