The time taken by a randomly selected student to fill out an online SOTE has a normal distribution with mean 2 minutes and standard deviation 45 seconds. Suppose 4 students fill out an online SOTE on a randomly selected day. Find the probability that the sample average amount of time taken is at most 3 minutes.
mean = = 2
standard deviation = = 45 seconds. =0.75 minutes
n = 4
= / n = 0.75 / 4=0.375
P( < 3) = P[( - ) / < (3-2) /0.375 ]
= P(z <2.67)
Using z table
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