Question 916211: The accompanying data table lists measured voltage amounts supplied directly to a familys home. The power supply company states that that it has a target power supply of 120 volts. Using those home voltage amounts, test the claim that the mean is 120 volts. Use a 0.10 significance level.
Day Volts
1 124.2
2 123.9
3 123.9
4 124.5
5 123.4
6 123.3
7 123.3
8 123.6
9 123.5
10 123.9
11 123.5
12 123.7
13 123.8
14 123.7
15 123.9
16 124.0
17 124.2
18 123.9
19 123.8
20 123.8
21 124.0
22 123.9
23 123.6
24 124.1
25 123.4
26 123.4
27 123.4
28 123.4
29 123.3
30 124.4
31 123.5
32 123.6
33 123.9
34 123.9
35 123.9
36 123.8
37 123.9
38 123.7
39 123.8
40 123.8
A) CALCULATE THE TEST STATISTIC ________
B) IDENTIFY THE CRITICAL VALUE __________
Answer by ewatrrr(24785)   (Show Source):
You can put this solution on YOUR website! Re TY
Ho mean = 120
Ha mean ≠ 120
two- tailed testing as written above: .05 on either side
Sample: mean = 123.7625 and s = .293247
The assignment called for the t-test: t = (x-bar-120)/(s/√n)
Critical value is then ± 1.685, invT(.05,49)& invT(.95, 49)
.....
As to desired t(sample mean)= 81.147 = 3.7625/.0463664 = 81.147
Obtaining that exact number to the thousandths place... will depend on decimal points used along the way..
Important, is that t(123.7625) so far exceeds the critical value, Ho is rejected.
Wish You the Best in your Studies.
1. Always important to know number of decimal points that are expected for the desired answer as to: (x-bar-120)/(s/√n) for ex
2. Does the exercise call for the t-test
If Population SD is unknown, t-test is recommended.
3. The Ho and Ha as written above calls for a two tailed.
That is t(123.76)= 81.147 was to be compared to critical t-value 1.635
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