Question

The life of headlamp bulbs is normally distributed with a mean of 300 hours and a standard deviation of 15 hours. Determine the range of 80% of the headlamp bulbs

Answer 1

Do you know how to use a normal distribution table?

Answer 2

yes kind of

Answer 3

So what would the z score be for 80%? Start with that.

Answer 4

See, once you know the SD, you have the fact that 1SD=15 hours. So whatever the SD will be, you can say \(300\pm z15\)

Answer 5

okay ....

Answer 6

Do you have a z score table in your book?

Answer 7

yes

Answer 8

Did you look it up? Ay issues? your .... seems like you were unsure about something still.