Question

The life expectancy of a typical lightbulb is normally distributed with a mean of 3,000 hours and a standard deviation of 38 hours. What is the probability that a lightbulb will last between 2,975 and 3,050 hours?

0.5565

0.6520

0.3545

0.6250

Answer 1

you gotta be kidding!!

Answer 2

Most serious xD

Answer 3

we will cheat, give me a moment

Answer 4

okay c:

Answer 5

http://davidmlane.com/hyperstat/z_table.html

Answer 6

looks like \(.6506\)

Answer 7

Well, We have .6520?

Answer 8

i guess go with that one