In: Statistics and Probability
In 1997, a survey of 840 households showed that 131of them use e-mail. Use those sample results to test the claim that more than 15% of households use e-mail. Use a 0.05 significance level. Use this information to answer the following questions.
Solution :
Given that,
= 0.15
1 - =0.85
n = 840
x = 131
Level of significance = = 0.05
Point estimate = sample proportion = = x / n = 131/840 = 0.156
This a right (One) tailed test.
Ho: p = 0.15
Ha: p 0.15
Test statistics
z = ( - ) / *(1-) / n
= ( 0.156 - 0.15) / (0.15*0.85) /840
= 0.49
P-value = P(Z>z)
= 1 - P(Z <z )
= 1- P(Z < 0.49)
= 1 - 0.6241
= 0.3759
The p-value is p = 0.3759, and since p = 0.3759 >0.05, it is concluded that the null hypothesis is not rejected.
Conclusion:
It is concluded that the null hypothesis Ho is not rejected. Therefore there is no enough evidence to claim that the population
proportion is greater than 0.15 at 0.05 level o0f significance.