Question 1050444
​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 &#8804; 45).
P = normalcdf(-9999,45, 57, 3.5)