In a random sample of 500 people aged 20-24, 22 were smokers. In ...

[cherise1989]

In a random sample of 500 people aged 20-24, 22 were smokers. In a random sample of 450 people aged 25-29, 14 were smokers.
 
  Do the data provide sufficient evidence to conclude that the proportion of smokers in the 20-24 age group is different from the proportion of smokers in the 25-29 age group? Use a significance level of 0.01.

Question 2

Suppose that you know the area under the standard normal curve to the right of 2 and the area under the standard normal curve to the right of 1.
 
  Without further consulting a table of areas, how could you find the area under the standard normal curve between 1 and 2? Explain your reasoning.

[bdobbins]

Answer to Question 1

H0: p1 = p2, Ha: p1  p2.
 = 0.01
Test statistic: z = 3.19. P-value = 0.0014
Reject the null hypothesis. At the 1 significance level the data provide sufficient evidence to conclude that the proportion of smokers in the 20-24 age group is different from the proportion of smokers in the 25-29 age group.

Answer to Question 2

The area under the standard normal curve between 1 and 2 can be found by subtracting the area to the right of 2 from the area to the right of 1.

[cherise1989]

Thanks for the timely response, appreciate it

[marict]

Excellent