Question

A researcher is testing the claim that adults consume an average of at least 1.85 cups of coffee per day. A sample of 35 adults shows a sample mean of 1.70 cups per day with a sample standard deviation of 0.4 cups per day. Test the claim at a 5% level of significance. What is your conclusion?

*Please explain each step, I just don't get it

Answer 1

Solution :

Given that,

Population mean = = 1.85

Sample mean = = 1.70

Sample standard deviation = s = 0.4

Sample size = n = 35

Level of significance = = 0.05

This is a left (One) tailed test,

The null and alternative hypothesis is,  

Ho: 1.85

Ha: 1.85

The test statistics,

t = ( - )/ (s/)

= ( 1.70 - 1.85 ) / ( 0.4 /35 )

= -2.219

P- Value = 0.0166

The p-value is p = 0.0166 < 0.05 it is concluded that the null hypothesis is rejected.

Conclusion :

It is concluded that the null hypothesis Ho is rejected. Therefore, there is enough evidence to claim that adults consume an average of at least 1.85 cups of coffee per day, at the 0.05 significance level.