A research team is testing whether a fuel aditive increases a car's gas mileage. The maker of the additive claims that the additive will increase a car's gas mileage by at least 6 mpg. Among 25 cars that were treated with the additive, the average increase in mileage was 5.3 mpg with a standard deviation of 1.8 mpg. The research team found the z-score to be -1.94. Is there enough evidence to reject the company's evidence?

Yes  there is sufficient evidence to  reject the company's evidence

Step-by-step explanation:

From the question we are told that  

   The sample size is  n =  25

    The mean is  

     The standard deviation is  

    The z-score is  z = -1.94

The null hypothesis is  

The alternative hypothesis is  

 Generally the p-value is mathematically evaluated as  

From the z table  the area under the normal curve to the left corresponding to    -1.94  is

=>  

=>  

Let assume the level of significance is  

 Hence the   this mean that

   The  decision rule is  

Fail to reject the null hypothesis

The conclusion is

 There is sufficient evidence to  reject the company's evidence

i used to know but i learned it a long time ago sorry

step-by-step explanation:

the answer is here: : )

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