Two random samples of31individuals were selected. One sample participated in an activity which simulates hard work. The average breath rate of these individuals was21breaths per minute. The other sample did some normal walking. The mean breath rate of these individuals was 13. Find the 95%confidence interval of the difference in the breath rates if the population standard deviation was4for breath rate per minute. Use 1 for the mean breath rate of individuals stimulated with hard work. Round the answers to one decimal place.

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