The national health interview survey conducted of 33,326 adults by the u. s. national center for health statistics in 2003 indicated that 21.4% of adults were current smokers. a similar study conducted in 1991 of 42,000 adults indicated that 25.6% were current smokers. we will use the subscript "1" for the year 1991 and the subscript "2" for the year 2003. (a) find a point estimate of the difference between the proportion of current smokers in 1991 and the proportion of current smokers in 2003. use 3 decimal places.

0.042

Step-by-step explanation:

Point estimate of the difference between the two population proportion :-

, where and are sample proportions.

Given : In 1991 survey , The proportion of adults were current smokers =25.6%

i.e.

In 2003 survey , The proportion of adults were current smokers = 21.4%

i.e. =0.214

Then , the point estimate of the difference between the proportion of current smokers in 1991 and the proportion of current smokers in 2003 :-

Hence, a point estimate of the difference between the proportion of current smokers in 1991 and the proportion of current smokers in 2003= 0.042

answer is  

a.

5.2 inches

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