solve it correctly please. I will rate accordingly. my last attempt...

All students in computer science in a local university have been asked to prove their proficiency in the use of statistical package by taking a proficiency test. The school found that the mean test score has been u = 80 with a standard deviation of o = 12. Assume the scores follow normal distribution. A survey of 19 students is taken. The probability that the sample mean score of these students is at least 77 is [1]