The correct answer would be C) 3%
Probability that you will get exactly 4 tails, if you flip a fair coin 7 times is: 
Step-by-step explanation:
We need to find the probability that you will get exactly 4 tails, if you flip a fair coin 7 times.
This is the combination question.
The total combinations will be: 2^7=128
Now, finding number of ways we can get exactly 4 tiles:
We will use the formula:

in our given question, n= 7, k= 4
Putting values:

So, Probability that you will get exactly 4 tails, if you flip a fair coin 7 times is: 
Keywords: Probability
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Answer:
c) t-test of population mean
Explanation:
The t-test statistic is used in hypothesis testing. Here we would use a one sample t test to test our hypothesis. The one sample t test measures the statistical difference between the hypothesized mean and the sample mean. In a one sample t test or single sample t test, a test variable is measured against a test value.
Example we compare our test variable to the hypothesized mean value $75 above.
The t test is used instead of z score when standard deviation is unknown.
Using the t test, we either accept or reject the null hypothesis given alternative hypothesis.