40% of a certain number is 80 what is that number ?
2 answers:
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<h2>Answer with explanation:</h2>
As per given , we have
Since , alternative hypothesis is right tailed, so the test is a right tailed test.
n= 1987
Proportion of adults believe that rudeness is a worsening problem :
Test statistic :
(since , the normal curve takes values of z from -7 to 7, so we use critical value to draw conclusion.)
The critical value for a significance level of 0.005= 1.645
Since , absolute test statistic value (12.09) is greater than the critical value (1.645), it means there is statistical significance and so we reject the null hypothesis.