Ascrap metal dealer claims that the mean of his cash scales is "no more than $80," but an internal revenue service agent believes the dealer is truthful. observing a sample of 20 cash customers, the agent finds the mean purchases to be $91, with a standard deviation of $21. assuming the population is approximately normally distributed, and using the 0.05 level of significance, what is the calculated value of test statistic

2.3425

Step-by-step explanation:

As per given , we have

n = 20

We assume that the population is approximately normally distributed.

Since population standard deviation is unknown , so we use t-test.

Test statistic :

Hence, the calculated value of test statistic = 2.3425

step-by-step explanation:

you can add the two numbers and divide the result by 2. or you can find the gap between the two numbers and add half of this to the smaller number.