Question

The vocabulary test scores for the population of third graders is normally distributed with a mean of 60 and a standard deviation of 12.
What percentage of third graders score less than 48?

Answer 1

since 60 is the mean, it is at 50%, since it says 48%, it should be numbers lower than 60

Answer 2

Score should be less than 48

Answer 3

oh sorry read it wrong

Answer 4

alright 48 is 1 standard deviation away from 60
because 60-12=48
thus it is in the zone of around 19%
use the graph:
http://www.regentsprep.org/regents/math/algtrig/ATS2/NormalLesson.htm

Answer 5

How to find "alright 48 is 1 standard deviation away from 60"?

Answer 6

well it says 1 standard deviation is 12 so you do 12+60 and 60-12 to get 1 standard deviation
since it 48 is lower, you subtract 12
thus you do 60-12
and coincidently you get 48 which is 1 standard deviation

Answer 7

for example if it says scored 72, its higher than 60 so you add 12 to 60
basically you do the
(mean -standard deviation) -if it is lower than the mean
(mean+ standard deviation)-is it is higher than the mean

Answer 8

The vocabulary test scores for the population of third graders is normally distributed with a mean of 60 and a standard deviation of 12.
What percentage of third graders score more than 84?

Answer 9

it should be 2 S.D as (60 + 12 x2)

Am i correct?

Answer 10

yes its 2 standard deviation thus its 19%+15%

Answer 11

options are same for the both questions
(a) 2.5%

(b) 5%

(c) 16%

(d) 32%

Answer 12

so for first it should be 16% an second one 32%.

Is that correct?

Answer 13

yes

Answer 14

Thanks, and could you help in finding the exact percentage, like if in case options are not given

Answer 15

gee havent done it in a year...ummm im not sure sorry i cant help you with that

Answer 16

thanks again for the support :)

Answer 17

no prob
asian at your service :)