John Wiley & Sons TI-83 User Manual download pdf (Page 87)

Since the p-value is less than our significance level 2.5%, we reject the null hypothesis. The data

leads us to conclude that the diet does lower the median systolic blood pressure of adults.

Example: Math Anxiety

Many students suffer from math anxiety. A statistics professor offered her students a two-hour

lecture on math anxiety and ways to overcome it. A total 79 of 42 students attended this lecture.

The students were given similar statistics tests before and after the lecture. Thirty-three of the

forty-two students scored higher on the tests after the lecture, seven scored lower after the

lecture, and two scored the same on both tests. Using a 1% significance level, can you conclude

that the median score of students increases as a result of attending this lecture? Assume that these

42 students constitute a random sample of all students who suffer from math anxiety. Our

hypotheses are H0 : the lecture does not increase the median score versus H1 : the lecture does

increase the median score.

We use 1-PropZTest with x = 33 and n = 42. The p-value is 1.064 × 10−4, which is less than

our significance level 1%. We reject the null hypothesis and conclude that the lecture does raise

the median score.

Exercises

1. Test at a 5% significance level whether or not the population median is over 10 given the

following sample data:

9 11 8 16 8 8 12 15 16 10 10 9

2. One hundred cell-phone customers who have changed their service provider from Company

A to Company B are chosen at random. Sixty-three of the customers have lowered their

monthly bills, twenty-seven of the customers have higher monthly bills, and the remaining ten

customers report having roughly the same monthly bills. Test at a 5% significance level

whether the median costs per month for Company B are lower than those for Company A.

Solutions

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John Wiley & Sons TI-83 User Manual Page 87