120 is the same as 394 fewer than Z
2 answers:
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Answer:
Step-by-step explanation:
Data given and notation
represent the sample mean given
represent the population standard deviation
sample size
represent the value that we want to test
t would represent the statistic (variable of interest)
State the null and alternative hypotheses.
We need to conduct a hypothesis in order to check if the true mean for the gasoline prices is lower than 1.25, the system of hypothesis would be:
Null hypothesis:
Alternative hypothesis:
If we analyze the size for the sample is > 30 but we don't know the population deviation so is better apply a t test to compare the actual mean to the reference value, and the statistic is given by:
(1)
Calculate the statistic
We can replace in formula (1) the info given like this: