Problem 82

Given information

Marketing companies have collected data implying that teenage girls use more ring tones on their cellular phones than teenage boys do. In one particular study of    randomly chosen teenage girls and boys (  of each) with cellular phones, the mean number of ring tones for the girls was  with a standard deviation of . The mean for the boys was  with a standard deviation of .

Step-by-step explanation

As the given information is the problem reveals, in one particular study of    randomly chosen teenage girls and boys (  of each) with cellular phones, the mean number of ring tones for the girls was  with a standard deviation of . The mean for the boys was  with a standard deviation of .

Now, consider the following observations:

The null hypothesis is defined as follows:

The alternative hypothesis is stated as follows:

  The difference between mechanical and electrical engineers means entry-level salary is .

   Student’s t (sample t-test, variances not pooled).

For the mean difference, the paired test static is,

After ENTER all of the values, look at the OUTPUT below.

Test statistic .  

The   from the output is .  

Drawing a representation of the situation using the information from the last exercise.

The horizontal axis should be clearly labeled and scaled, and the region(s) matching the  should be shaded on the graph.

   Decision: Null hypothesis is rejected.

    Conclusion: At the   significance level, there is sufficient evidence to infer that girls have a larger average number of ringtones than boys.

Therefore,

there is enough evidence to conclude that the mean number of ringtones for girls is higher than that for boys.