Scores on a test are normally distributed with a mean of 68.2 and a standard deviation of 10.4. What is the probability that among 75 randomly selected students, at least 20 of them score greater than 78?
1 Answer
Explanation:
Let say,
therefore,
To find a probability that at least more than 20 of 75 students score greater than 78 marks,
where
We also can calculate as