+1993 
Can you explain why , so I understand?
2) A normal distribution has a mean of 102 and a standard deviation of 2.9.
What is the z-score of 105?
Enter your answer, rounded to the nearest hundredth.
Answer is 1.03
+128406 Don't know about the first....but......here's the second one....
[ 105 - 102 ]
__________ =
2.9
3
____ =
2.9
1.03
+128406 [ 165 - 176 ]
_________ = z score we are looking for
11.4
-11
____ ≈ -.96
11. 4
Looking at the table here : http://www.z-table.com/
This corresponds to .1685
So....about 16.85% of the 120 will weigh < 165 lbs
So.....this means that 120 ( 1 - .1685) ≈ 99.78 will weigh > 165 lbs
So 99.78 will round to 100
Good job !!!
+1993 Im so glad Im understanding these! Im going to be uplaoding more to double check not sure if you would like to but if you do that would be great.
Here is another one.
Now this one I was a bit confused but maybe I did it correctly
+1993 
I got 68.08 but what does this mean exactly ? That all the scores are below 68 ?
+128406 16% corresponds to either a z score of -.99 OR a z score of 1
So we either have that
[ score - 76 ]
___________ = -.99 multiply both sides by 8
8
score - 76 = -7.92 add 76 to both sides
score = 68.08......which means that 16% will be below about 68
OR
[ score - 76 ]
__________ = 1 multiply both sides by 8
8
score - 76 = 8 add 76 to both sides
score = 84 .....this means that 16% will be above 84
But...since this isn't one of your choices......68 is correct
[ Note that the 16% could be anywhere. for example....it could also mean the 16% "cluster" on either side of the mean ]
+1993 Since your online again, I was kind of confused on this one as to why you said " Since this isnt your choice it is 68"
+128406 OK
30% = .30 which corresponds to a z score ≈ -.52
So....we have
[ weight we are looking for - mean ]
_____________________________ = -.52
std dev
[ weight we are looking for - 143 ]
___________________________ = -.52 multiply both sides by 4.2
4.2
weight we are looking for - 143 = -2.184 add 143 to oth sides
weight we are looking for = 140.8 g (round to 141 g )
Good JOB !!!....I think you got it !!!
+1993 Yay! I am so happy im understanding it thank you for your detialed explanations !
+1993 I see it now! That was a confusing but from your explaintions it makes more sense. 
Thank you for your help CPhill
+128406 OK.....glad to help.....sorry I don't know the answer(s) to the first one....I hate to "guess" and maybe give incorrect answers......
+1993 No its okay you have been plenty of help maybe ElectricPavlov can help me on it when he gets online. Im gonna repost the question in case he doesnt see it here. Thank you again
