Statistics homework help?
The charge life of a certain battery for cell phones is normally distributed with a mean of 200 minutes and a standard deviation of 40 minutes.
What is the probability that a random sample of 16 of these batteries has an average charge life of less than 180 minutes?
- 3 weeks ago
The sample is normally distributed with a standard deviation 40/√16 = 40/4 = 10 minutes.
P(x <= 180) = P[(x-200)/10 <= (180-200)/10] = P(z <= -2) = 0.023