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Test 4
6.
A survey asked, “How many tattoos do you currently have on your body?” Of the 1249 males surveyed, 196 responded that they had at least one tattoo. Of the 1002 females surveyed, 149 responded that they had at least one tattoo. Construct a 90% confidence interval to judge whether the proportion of males that have at least one tattoo differs significantly from the proportion of females that have at least one tattoo. Interpret the interval.
Let p1 represent the proportion of males with tattoos and p2 represent the proportion of females with tattoos. Find the 90% confidence interval for p1−p2.
The lower bound is
The upper bound is
Interpret the interval.
- There is 90% confidence that the difference of the proportions is in the interval. Conclude that there isinsufficient evidence of a significant difference in the proportion of males and females that have at least one tattoo.
- There is a 90% probability that the difference of the proportions is in the interval. Conclude that there is a significant difference in the proportion of males and females that have at least one tattoo.
- There is 90% confidence that the difference of the proportions is in the interval. Conclude that there is a significant difference in the proportion of males and females that have at least one tattoo.
- There is a 90% probability that the difference of the proportions is in the interval. Conclude that there is insufficient evidence of a significant difference in the proportion of males and females that have at least one tattoo.