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LuckyWell [14K]
3 years ago
13

An Electrician charges $30 for a service call plus $75 per hour of service. If he charged 210 how many hours did he work?

Mathematics
1 answer:
andreyandreev [35.5K]3 years ago
3 0
30 + 75x= 210
Subtract 30 from both sides
75x=180
Divide both sides by 75
X =2.4

Worked 2.4 hours
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Hello!

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1. To manually calculate the mean square between the groups you have to calculate the sum of square between conditions and divide it by the degrees of freedom.

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∑ni(Ÿi - Ÿ..)²

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Ÿ..= general mean is the mean that results of all the groups together.

General mean:

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Se²=<u> (n₁-1)S₁² + -(n₂-1)S₂² + (n₃-1)S₃²</u>

                        n₁+n₂+n₃-k

Se²=<u> 19*14.3 + 19*17.2 + 19*16.7 </u>= <u>  915.8   </u>  = 16.067

                 20+20+20-3                  57

DfE= N-k = 60-3= 57

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F= \frac{Mean square B}{Mean square E} = \frac{5.32}{16.067} = 0.33

4. P(F_{2; 57} ≤ F) = P(F_{2; 57} ≤ 0.33) = 0.28

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