# Math Help - Normal distribution.

1. ## Normal distribution.

Right, so I've missed quite alot in school and now started revising earlier than I would've. It might not even fall under the 'Advanced' category, sorry if that's the case. Stats don't make sense to me at all so please help.

If the costs of completion of a building are normally distributed with a mean of $700,000 and a standard deviation of$150,000, what are the chances of making a profit if the promised return is $1,000,000 and how much has to be obtained in order to have a 90% chance of making a profit? Cheers for any tips. 2. Ok, it seems you should find a z-score here. $\displaystyle z=\frac{x-\mu}{\sigma} =\frac{x-700000}{150000}$ Now is the 1000000 also a building cost? if so make it $x$ in the above equation. 3. Nah, the$1bn is not the building cost, it's supposed to be expected profit which confuses me quite alot

4. I thought so, that isn't to helpful in this situation. Did you post the whole question?

Just for your reference, its actually 1 million dollars not 1 billion.