B was incorrect...please help
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Answer:
We conclude that the mean Ohio score is below the national average.
Step-by-step explanation:
We are given that a random survey of 1000 students nationwide showed a mean ACT score of 21.1. Ohio was not used.
A survey of 500 randomly selected Ohio scores showed a mean of 20.8. The population standard deviation is 3.
<u><em>Let </em></u><u><em> = mean Ohio scores.</em></u>
So, Null Hypothesis, :
21.1 {means that the mean Ohio score is above or equal the national average}
Alternate Hypothesis, :
< 21.1 {means that the mean Ohio score is below the national average}
The test statistics that would be used here <u>One-sample z test statistics</u> as we know about population standard deviation;
T.S. = ~ N(0,1)
where, = sample mean Ohio score = 20.8
= population standard deviation = 3
n = sample of Ohio = 500
So, <u><em>test statistics</em></u> =
= -2.24
The value of z test statistics is -2.24.
<em>Now, at 0.1 significance level the z table gives critical value of -1.2816 for left-tailed test.</em><em> Since our test statistics is less than the critical values of z as -2.24 < 1.2816, so we have sufficient evidence to reject our null hypothesis as it will fall in the rejection region due to which </em><em><u>we reject our null hypothesis</u></em><em>.</em>
Therefore, we conclude that the mean Ohio score is below the national average.