Please help. I have no idea what I am doing
Use the standard normal (z score) table to find: P(-1.00 ≤ z)
&
Find the probability that a data value picked at random from a normal population will have a standard score (z) that lies between the following pairs of z-values.
z = 0 to z = 2.10
-1.00 ≤ z is the same as z ≥ -1
or
1 - P(z ≤ -1.00) ----> .8413
I don't know how old your tables are or what they look like, but for most of them ...
here is a typical one:
http://www.stat.ufl.edu/~athienit/Tables/Ztable.pdf
find -1.0 in the horizontal under the 00 vertical to get . 1587
so
1 - P(z ≤ -1.00)
= 1 - .1587 = .8413
Of course with internet access, the use of tables is obsolete and we use on-line applets like this one:
http://davidmlane.com/normal.html
since you want the values above a z-score of -1
leave the mean at 0
and the SD at 1
click on "above" and enter -1
read .8413 in the answer window.
Sure, I'd be happy to help you with that!
To find P(-1.00 ≤ z), we need to use the standard normal (z-score) table. This table provides the probability of a standard normal distribution up to a certain z-value.
1. Start by opening the standard normal (z-score) table. You can find this table in many statistics textbooks or online resources.
2. Locate the row in the table that corresponds to the first digit of the z-value. In this case, the first digit of -1.00 is -1.0. Find the row that starts with -1.0.
3. Move along the row to find the column that corresponds to the second digit of the z-value. In this case, the second digit of -1.00 is 0.0. Find the column that starts with 0.0.
4. The cell at the intersection of the row and column will give you the probability up to that z-value. In this case, the cell will give you the probability up to -1.00.
5. Read the value in the cell. This will be the probability P(-1.00 ≤ z).
For the second part of your question, to find the probability that a data value picked at random from a normal population will have a standard score (z) that lies between the z-values 0 and 2.10:
1. Open the standard normal (z-score) table again.
2. Locate the row that corresponds to the first z-value, which is 0.0.
3. Move along the row to find the column that corresponds to the second z-value, which is 2.10.
4. The cell at the intersection of the row and column will give you the probability between those two z-values.
5. Read the value in the cell. This will be the probability that a data value picked at random from a normal population will have a standard score (z) between 0 and 2.10.
Remember, the standard normal (z-score) table provides probabilities up to a given z-value. If you need to find the probability beyond a certain z-value, you may need to use complementary probabilities or interpolation techniques.