Question

The power supply company states 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 0.01 significance level.
Day Volts
1 123.9
2 123.9
3 123.9
4 124.3
5 123.4
6 123.3
7 123.3
8 123.6
9 123.5
10 124.1
11 123.5
12 123.7
13 123.6
14 123.7
15 123.9
16 124.0
17 124.2
18 123.7
19 123.8
20 123.8
21 124.0
22 123.9
23 123.6
24 123.5
25 123.4
26 123.4
27 123.4
28 123.4
29 123.3
30 123.9
31 123.5