|
Science Forum Index » Statistics - Math Forum » Normal Distribution Probability problem. Please help!
Page 1 of 1
|
| Author |
Message |
| Guest |
 Posted: Thu May 01, 2008 8:25 am |
|
|
|
|
A year-group at the local secondary school consists of 100 boys and 81
girls. The heights of the boys may be assumed to be distributed
Normally with mean 160 cm and variance 16 cm^2, and the heights of the
girls to be distributed Normally with mean 150 cm and variance 9 cm^2.
(a) Find the probability that a randomly chosen student from the year-
group is more than 156.0 cm tall.
(b) Find the probability that the mean height of the year-group is 156
cm to the nearest cm.
I have an idea on how to tackle (a) but I'm not sure. However, I'm
going nuts over (b). |
|
|
| Back to top |
|
| jojo |
| Posted: Thu May 01, 2008 4:05 pm |
|
|
|
Guest
|
hoolash@gmail.com wrote:
Quote: (b) Find the probability that the mean height of the year-group is 156
cm to the nearest cm.
Mean height is a random variable and has got some distribution (under
the assumptions of this problem). You should be able to get parameters
of that distribution. "156 cm to the nearest cm" is just a descriptive
way of specifying an interval.
Your question is now: P(a<=X<b)=?
JoJO |
|
|
| Back to top |
|
| |
