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Weather-Related Deaths Review Exercise 5 involved weather-related U.S. deaths. Among the 450 deaths included in that exercise, 320 are males. Use a 0.05 significance level to test the claim that among those who die in weather-related deaths, the percentage of males is equal to 50%. Provide an explanation for the results.

Short Answer

Expert verified

There is enough evidence to warrant rejection of the claim that the percentage of male deaths out of the given sample ofweather-related deaths is equal to 50%.

It can be said that a comparatively greater number of males participate in outdoor activities like golfing, fishing and surfing during May, June and July. Thus, their proportion is greater than 0.5.

Step by step solution

01

Given information

It is given that out of 450 weather-related deaths, 320 were males.

02

Hypotheses

Letp is the population proportion of males who died.

The null hypothesis is as follows:

The proportion of male deaths is equal to 0.50.

Symbolically,

\({H_o}:p = 0.50\)

The alternative hypothesis is as follows:

The proportion of male deaths is not equal to 0.50.

Symbolically,

\({H_o}:p \ne 0.50\)

It is a two-tailed test.

03

Test statistic

Let\(\hat p\)denote the sample proportion of male deaths.

The value of\(\hat p\)is computed as shown below:

\(\begin{aligned}{c}\hat p = \frac{{{\rm{Number}}\;{\rm{of}}\;{\rm{male}}\;{\rm{deaths}}}}{{{\rm{Total}}\;{\rm{number}}\;{\rm{of}}\;{\rm{deaths}}}}\\ = \frac{{320}}{{450}}\\ = 0.711\end{aligned}\)

Here, p = 0.50.

Thus,

\[\begin{aligned}{c}q = 1 - p\\ = 1 - 0.50\\ = 0.50\end{aligned}\]

Since the sample size (n) equal to 450 is large, the value of the z-score is computed as follows:

\[\begin{aligned}{c}z = \frac{{\hat p - p}}{{\sqrt {\frac{{pq}}{n}} }}\;\;\; \sim N\left( {0,1} \right)\\ = \frac{{0.711 - 0.50}}{{\sqrt {\frac{{\left( {0.50} \right)\left( {0.50} \right)}}{{450}}} }}\\ = 8.957\end{aligned}\]

Thus, the test statistic, z is 8.957.

04

Obtain the critical value and the p-value

Refer to the standard normal table,

The critical value of z at 0.05 level of significance for a two-tailed test is equal to 1.96.

The corresponding p-value obtained using the test statistic is equal to 0.000.

05

Decision and conclusion of the test

Since the absolute value of the z-score is greater than the critical value and the p-value is less than 0.05, the null hypothesis is rejected.

There is enough evidence to conclude that the percentage of male deaths out of the given sample ofweather-related deaths is not equal to 50%.

06

Possible explanation for the results

It can be said that a comparatively greater number of males participate in outdoor activities like golfing, fishing and surfing during the months of May, June and July. Thus, their proportion is greater than 0.5.

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