Answer:
93.19%
Step-by-step explanation:
We have that the mean (m) is equal to 70.4, the standard deviation (sd) 11.1 and the sample size (n) = 140
They ask us for P (x =69)
For this, the first thing is to calculate z, which is given by the following equation:
z = (x - m) / (sd / (n ^ 1/2))
We have all these values, replacing we have:
z = (69 - 70.4) / (11.1 / (140 ^ (1/2)))
z = 1.49
With the normal distribution table (attached), we have that at that value, the probability is:
P (z <1.49) = 0.9319
The probability is 93.19%
