# Math Help - The normal distribution

1. ## The normal distribution

3. Using the standard normal distribution table, find the probability values of the following:

P(z < 1.8)
P( z > 1.8)
P(> -2.37)
P(1.76 < Z > 2.57)

any idea how to start this

2. is there a tutorial i can get
with formulas and stuff without using jus the calculator

3. Nope, this is just an exercise of reading values from a table or using technology to get the values.

If you have it just use excel

P(z < 1.8)

Code:
=normsdist(1.8)

P( z > 1.8)

Code:
=1-normsdist(1.8)

P(> -2.37)

Code:
=1-normsdist(-2.37)

P(1.76 < Z > 2.57) do you mean P(1.76 < Z < 2.57) ? if so

Code:
=normsdist(2.57)-normsdist(1.76)

4. =normsdist(1.8)
got 0.4641 on the table

now what to do from there

5. also got to do a sketch

6. Originally Posted by math321
=normsdist(1.8)
got 0.4641 on the table
P(Z<1.8) = 0.9641

You found P(0<Z<1.8) = 0.4641

7. so i have to add .5
is dat it

8. and for this 1 P( z > 1.8)
will it be .5 - .4691
or 1 - .4691

9. Originally Posted by math321
so i have to add .5
is dat it
Well that will get you the answer, but do you understand the process?

10. yep slightly better
and for this 1 P( z > 1.8)
will it be .5 - .4691
or 1 - .4691

11. Originally Posted by math321
yep slightly better
and for this 1 P( z > 1.8)
will it be .5 - .4691
or 1 - .4691
It will be neither of those.

P(Z>1.8) = 1-0.9641

You need to remember that P(Z<1.8)+P(X>1.8) = 1

12. can u give me an idea of how the graph will look please
starting to understand a little more

13. for this 1 P(> -2.37)

i got 1 - 0.0089 = .9911

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