The lifetime of a particular brand of A batteries follows a normal distribution. The mean lifetime of particular brand of A batteries is 1000 hours, with a standard deviation of 100 hours.
1. What percentage of batteries last more than 1100 hours?
a. 2.5%.
b. 5%.
c. 16%.
d. 32%.
2. What is the probability that a randomly selected battery lasts more than 875 hours?
a. 0.3749.
b. 0.8944.
c. 0.8716.
d. 0.1056.
3. What is the probability that a randomly selected battery lasts between 1150 and 1250 hours?
a. 0.2417.
b. 0.4332.
c. 0.9915.
d. 0.3085.