Question

Birthweights at a local hospital have a Normal distribution with a mean of 110 oz and a standard deviation of 15 oz.

The proportion of infants with birthweights above 125 oz is
A. 0.500.
B. 0.159.
C. 0.341.
D. 0.841.

The proportion of infants with birthweights between 125 oz and 140 oz is
A. 0.819.
B. 0.636.
C. 0.477.
D. 0.136.

Answer 1

I got C and D?

Answer 2

actally 1 might be B...

Answer 3

125 is 1 dev above so it's 13.5 + 2.35 so B?

Answer 4

and between 125 and 140 9s 13.6?

Answer 5

@mathnino

Answer 6

ok i guess you are struggling with this kind of questions.

Answer 7

let me bring up something that might help you out. a graph. i have to google this so it might take some time.

Answer 8

a little bit :).

Answer 9

http://historiesofcatastrophicdreaming.files.wordpress.com/2010/10/68-95-99.png?w=640

Answer 10

the 0 in the bottom represents the mean.

Answer 11

+1 / -1 represents the Z scores or how many standard deviations away from the mean it is.

Answer 12

so now we are looking at >1

Answer 13

13.5+2 =15.5 so B?

Answer 14

125-140 is bfrom 1-2 so 13.5%?

Answer 15

am i misisng somthing? :P

Answer 16

yes that is correct.

Answer 17

and for the first question, what would you get?

Answer 18

okay so it is what I said b4 B and D? :)

Answer 19

yessir.

Answer 20

weee okay :) SO I didn't get konfoosed on this one :P

Answer 21

:) hopefully you dont get confused anymore.

Answer 22

I sholdn't... Stats is >(. I rather do Calc 1 again...

Answer 23

Calc2 *

Answer 24

haha, i thought stat was easier.

Answer 25

i'm doing linear algebra which isn't that fun.. oh well.

Answer 26

Me too... >(