Question

The weights of packages of crackers follow a normal distribution with a mean of 15.2 oz. and a standard deviation of .5 oz. If x-bar is the mean weight of a SRS of 7 packages of crackers, then x-bar has an _______

Answer 1

@jim_thompson5910

Answer 2

OPTIONS:

(a) approx distrib with mean=15.2 and SD= .2
(b) exact normal distrib with mean=15.2 and SD=.4
(c)approx distrib with mean=15.5 and SD= .2
(d) approx distrib with mean= 15.5 and SD= .4
(e) exact distrib with mean=14.6 and SD= 1

Answer 3

well if X is normally distributed

then Xbar is normally distributed

Answer 4

Ok

Answer 5

oh sry i should add: Xbar is normally distributed for large values of n

Xbar is approximately normally distributed if X is normally distributed and n is a small number

Answer 6

ok

Answer 7

which option would that be?

Answer 8

?

Answer 9

what do you think?

Answer 10

uh

Answer 11

keep in mind that if X is normally distributed with mean mu and standard deviation sigma, then

Xbar is approximately normally distributed (for n < 30) with

mean = mu
standard deviation = sigma/sqrt(n)

Answer 12

so is it either a or d?

Answer 13

why d?

Answer 14

I mean, i think its a but im not sure

Answer 15

mean = 15.2

so it's either A or B

Answer 16

is it exactly normally distributed? or approximately normally distributed?

Answer 17

Umm norma?

Answer 18

approx

Answer 19

good

Answer 20

so it can't be B because that's exact

Answer 21

it's approx since n = 7 is definitely less than n = 30

Answer 22

So A then

Answer 23

yes

Answer 24

yay! ok like one more ill post now thanks so much

Answer 25

alright