Question 1050444: Suppose that the lifetimes of light bulbs are approximately normally distributed, with a mean of 57 hours and a standard deviation of 3.5 hours. With this information, answer the following questions.
(a) What proportion of light bulbs will last more than 62 hours?
(b) What proportion of light bulbs will last 53 hours or less?
(c) What proportion of light bulbs will last between 57 and 62 hours?
(d) What is the probability that a randomly selected light bulb lasts less than 45 hours?
How do I solve this using a TI calculator?
Answer by ewatrrr(24785)   (Show Source):
You can put this solution on YOUR website! mean of 57 hours and a standard deviation of 3.5 hours.
(a) What proportion of light bulbs will last more than 62 hours?
TI syntax is P = normalcdf(smaller, larger, µ, σ)
P = normalcdf(62, 9999, 57, 3.5) |Note: 9999 used as placeholder for larger
(b) What proportion of light bulbs will last 53 hours or less?
P = normalcdf(-9999,53, 57, 3.5)
(c) What proportion of light bulbs will last between 57 and 62 hours?
P = normalcdf(57,62, 57, 3.5)
(d) What is the probability that a randomly selected light bulb lasts less than 45 hours?
Since this is a continuous function, we have P(x < 45) = P(x ≤ 45).
P = normalcdf(-9999,45, 57, 3.5)
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