The average time for students in MUN to commute to the university from their home is claimed to be 20 minutes with standard deviation of 10 minutes.

The average time for students in MUN to commute to the university from their home is claimed to be 20 minutes with standard deviation of 10 minutes. Assuming the elapsing time (X) for the student population is normal. If a random sample of size 4 is taken, the probability value of P{10 ≤ X¯ ≤ 30} is: