Question

Bags of a certain brand of tortilla chips claim to have a net weight of 14 ounces. Net weights actually vary slightly from bag to bag and are Normally distributed with mean μ. A representative of a consumer advocate group wishes to see if there is any evidence that the mean net weight is less than advertised and so intends to test the hypotheses

H0: μ = 14, Ha: μ < 14.

To do this, he selects 16 bags of this brand at random and determines the net weight of each. He finds the sample mean to be = 13.88 and the sample standard deviation to be s = 0.24.
Reference: Ref 16-4

Based on these data,
A. we would reject H0 at significance level 0.10 but not at 0.05.
B. we would reject H0 at significance level 0.05 but not at 0.025.
C. we would reject H0 at significance level 0.025 but not at 0.01.
D. we would reject H0 at significance level 0.01.

Answer 1

@jim_thompson5910

Answer 2

The only significance levels I know of are 0.010 and 0.05.. A?

Answer 3

or how do you solve for the levels?!

Answer 4

Test Statistic:



t = (xbar-mu)/(s/sqrt(n))


t = (13.88-14)/(0.24/sqrt(16))


t = -2

Answer 5

n = 16 or 14?

Answer 6

there are 16 items in the sample, so n = 16

Answer 7

ic ic ok..

Answer 8

P-Value:

p = tcdf(-10,-2,15) = 0.03197

So you reject H0 if alpha = 0.05 or alpha = 0.10


http://www.wolframalpha.com/input/?i=tcdf%28-10%2C-2%2C15%29

Answer 9

SO... A!

Answer 10

no

Answer 11

Then I'm confused.. :(

Answer 12

you reject H0 if alpha = 0.05 or alpha = 0.10

Answer 13

Ic so A is false then. I'm not sure what Wolfram is exactly showing us....?

Answer 14

it's showing the p value

Answer 15

Ic hmm...

Answer 16

So how do we test the other levels?

Answer 17

Damn I'm in trouble... 4 Q's in 30 mins..... :(

Answer 18

"test the other levels"?

Answer 19

The Sig levels, for B, C and D?

Answer 20

oh, the p-value is 0.03197

so it's only significant if alpha is 0.05 or 0.10

so you're rejecting H0 if alpha is 0.05 or 0.10

Answer 21

Oh, so B?

Answer 22

but not at 0.025 since 0.03197 is not less than 0.025, so the answer is B

Answer 23

yeah

Answer 24

:) NEXT Q GOGOG FAST!