Mark B. answered • 11/27/17
Tutor
New to Wyzant
PhD Candidate in Psychology: Experienced Math, Statistics, Tutor
Hello Robert,
Hope you had a great Thanksgiving.
Okay, let me give you some steps and a link to "assist" you in solving your problem. I want you also to think about your value given of z = -0.77 and do a bit of logic in addition to the steps I give you. That way you become much more familiar with the why as well as the what, okay? Fair enough?
Go to your z-table. Here is a link to assist you.
Hope you had a great Thanksgiving.
Okay, let me give you some steps and a link to "assist" you in solving your problem. I want you also to think about your value given of z = -0.77 and do a bit of logic in addition to the steps I give you. That way you become much more familiar with the why as well as the what, okay? Fair enough?
Go to your z-table. Here is a link to assist you.
http://www.z-table.com/
Now, follow the following steps, okay?
Step 1: Split your given decimal into two "by DECIMAL PLACES." Please note: I am not yelling but just using caps for emphasis.
Example: Given the decimal of .45 I would want you to split that given decimal into .4 and .05 We good so far?
Step 2: Now, go down the left side of your z-score table and look at the .4. Do you see it? Once you identify that row, I want you to go directly to the .05 column which is identified as such at the top of the table. Do you see it? Notice .4 +.05 = .45 right? Okay, good.
Step 3: Go look at the intersection between the row and column of the given decimal. In the case I provided above, you will notice the intersection to have this value: 0.1736 Do you see it?
Now, if the value given you is positive, which in the above example I gave you, add 0.5000 to your score. Why? You are attempting to find the area to the LEFT of z and in the example I gave you one needs to remember to add for the .5000 area of the other half of the bell curve.
What if the value given is negative? Remember: the bell curve is symmetrical so if given a negative value just look up absolute value. For example, in your given value of -0.77 - and you are asked for the area to the LEFT of that value, you do the exact same thing by looking up the absolute value of -0.77 in the same way I just showed you. (0.77)
Here is where that logic part comes into play and I want to see if you can determine the answer: Remember before I give this question though that a negative z-score means the score is to the LEFT of the mean. Also, remember that all a z-score happens to be is a transformation of other values assigned to observations or measurements. Remember the area between one standard deviation above and below the mean. These are things which will assist you vastly as you work these problems. Back to my original point though: When using the z-score you have, do you add .5000 as you did with the positive, or, do you subtract from 1.000 (the entire area of the curve), or do nothing?
I hope this answers your question sufficiently, while allowing me to adhere to the academic honesty guidelines established by Wyzant, however if you are still experiencing difficulty, please follow up. In fact, follow up - if you would - so I know you understand what I just explained to you.
Have a great week at school. Be well!
Now, follow the following steps, okay?
Step 1: Split your given decimal into two "by DECIMAL PLACES." Please note: I am not yelling but just using caps for emphasis.
Example: Given the decimal of .45 I would want you to split that given decimal into .4 and .05 We good so far?
Step 2: Now, go down the left side of your z-score table and look at the .4. Do you see it? Once you identify that row, I want you to go directly to the .05 column which is identified as such at the top of the table. Do you see it? Notice .4 +.05 = .45 right? Okay, good.
Step 3: Go look at the intersection between the row and column of the given decimal. In the case I provided above, you will notice the intersection to have this value: 0.1736 Do you see it?
Now, if the value given you is positive, which in the above example I gave you, add 0.5000 to your score. Why? You are attempting to find the area to the LEFT of z and in the example I gave you one needs to remember to add for the .5000 area of the other half of the bell curve.
What if the value given is negative? Remember: the bell curve is symmetrical so if given a negative value just look up absolute value. For example, in your given value of -0.77 - and you are asked for the area to the LEFT of that value, you do the exact same thing by looking up the absolute value of -0.77 in the same way I just showed you. (0.77)
Here is where that logic part comes into play and I want to see if you can determine the answer: Remember before I give this question though that a negative z-score means the score is to the LEFT of the mean. Also, remember that all a z-score happens to be is a transformation of other values assigned to observations or measurements. Remember the area between one standard deviation above and below the mean. These are things which will assist you vastly as you work these problems. Back to my original point though: When using the z-score you have, do you add .5000 as you did with the positive, or, do you subtract from 1.000 (the entire area of the curve), or do nothing?
I hope this answers your question sufficiently, while allowing me to adhere to the academic honesty guidelines established by Wyzant, however if you are still experiencing difficulty, please follow up. In fact, follow up - if you would - so I know you understand what I just explained to you.
Have a great week at school. Be well!
