A survey of 430 randomly selected adults found that 21% of the 222 men and 18% of the 208

Remember that given problems such as this, you are required to assess the claim using the z test for proportions.   Take the sample of males to be from population 1 and the sample for females to be population two.  The alternative hypothesis is a right-tailed test.

Hypotheses

H0: pm - pf  = 0

Ha: pm - pf > 0.

Formula for testing a difference in proportions.

Z  =   (0.21- 0.18)/(sqrt((0.21*(1-0.21))/222) + (0.18*(1-0.18))/208)  =  1.07

If the test is conducted at the 0.05 level of significance, then the critical value will be,  1.64, Compare  the test statistic above, for the t-test (1.07) and compare it with the critical value, if the test statistic calculated is greater then we conclude that the proportion of males is significantly greater. For this case, we fail reject the null hypothesis. 

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