Badgers said:I just wanted to post so I am associated with this discussion.
As you were.....

Im working my way through equations! Stuff is actually coming back to me.
Im about to do this one, race you Badgers!
- Batteries for a radio have a mean life of 160 hours and a standard deviation of 30 hours. Assuming the battery life follows a normal distribution, calculate:
(a) The proportion of batteries which have a life of between 150 hours and 180 hours.
( b)The range (symmetrical about the mean) within which 75% of batteries lie.