| The Problem |
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A survey of 120 females showed that 18 did not wish to work after marriage. Find the 95% confidence interval of the true proportion of females who do not wish to work after marriage. |
From the statement of the problem we have n = 120, x = 18. We are looking for a 95% confidence interval of the proportion. Thus, we use the TI83/84 1-PropZInt function.
Press STAT and right arrow twice to TESTS. Arrow down to A:1-PropZInt and press ENTER to select it. Enter 18 for x. Arrow down once and enter 120 for n. Arrow down once and enter .95 for C-level.
Arrow down one last time and press ENTER. The calculation will now be preformed, and the results are shown below.
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The 95% confidence interval of the proportion is .086 < p < .214.
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