6 A medical facility used powered gurneys tools that have a

6. A medical facility used powered gurneys tools that have a length of life that is approximately normally distributed with mean equal to 8000 hours and a standard deviation of 1600 hours. Find the probability that a random sample of 36 gurneys will have an average life of less than 7500 hours. Assumed (or Approximately) Normal Distribution (n Large)

Solution

MEan = u = 8000

SD = 1600

n = 36

x = 7500

z = (x - u) / (SD / sqrt(n))

z = (7500 - 8000) / (1600 / sqrt(36))

z = -1.875

We are looking for P(z < -1.875)

0.0304 ---> ANSWER