Answer :
The test statistic for the student who scored 79.6 points on the exam is 1.38
The relationship between a value and the mean of a group of values is quantified by a Z-score. The Z-score is calculated using standard deviations from the mean. A Z-score of zero means the data point's score is equal to the mean score.
Formula for z-score = x - u / σ
According to the question,
Sample size = 20 grades
Mean of sample = 74.8
Sample Standard deviation = 15.5
We have to calculate z-score for the student who scored 79.6 points on the exam.
But here if we see , sample size is less than 30 and population standard deviation is unknown.
So, we can't use Z-score .
t-statistics = x - u / (s/√n)
=> 79.6 - 74.8 / ( 15.5 / √20)
=> 4.8√20 / 15.5
=> 1.38 is required answer
To know more about z-score here
https://brainly.com/question/15016913
#SPJ4