# Normal distribution question

• Dec 23rd 2008, 06:12 AM
smidga
Normal distribution question
I've got a question here the importants parts of it
regulations say bacteria, per litre of seawater, must be less than 4
rate of occurance of this bacteria at a beach, is 4.6 per litre of sea water
it asks me to say what probabilty distribution to use, i'm sure its the normal distribution
use the distribution to find the prob that this beach will fail the regulations

how am i supposed to do this becasue all the example i have to use the normal distribution involve the mean and sd.

Please could someone explain or solve this for me
• Dec 23rd 2008, 07:40 AM
hatsoff
Quote:

Originally Posted by smidga
I've got a question here the importants parts of it
regulations say bacteria, per litre of seawater, must be less than 4
rate of occurance of this bacteria at a beach, is 4.6 per litre of sea water
it asks me to say what probabilty distribution to use, i'm sure its the normal distribution
use the distribution to find the prob that this beach will fail the regulations

how am i supposed to do this becasue all the example i have to use the normal distribution involve the mean and sd.

Please could someone explain or solve this for me

4.6 cells in an entire litre of seawater? 4.6 million cells? How many litres were tested? We need more detail.

Try posting the original question, word-for-word.
• Dec 25th 2008, 02:01 PM
awkward
Quote:

Originally Posted by smidga
I've got a question here the importants parts of it
regulations say bacteria, per litre of seawater, must be less than 4
rate of occurance of this bacteria at a beach, is 4.6 per litre of sea water
it asks me to say what probabilty distribution to use, i'm sure its the normal distribution
use the distribution to find the prob that this beach will fail the regulations

how am i supposed to do this becasue all the example i have to use the normal distribution involve the mean and sd.

Please could someone explain or solve this for me

The Poisson distribution may be appropriate here.