SOLUTION: The average score in the entrance examination in Mathematics at CBN High School is 80 with a standard deviation of 10.A random sample of 40 students was taken from these year's exa
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Question 1061944: The average score in the entrance examination in Mathematics at CBN High School is 80 with a standard deviation of 10.A random sample of 40 students was taken from these year's examinees and it was found to have a mean score of 84.Does this indicates that this year's batch is better than the previous batches? Answer by rothauserc(4718) (Show Source):
You can put this solution on YOUR website! The problem has to state a significance level, usually if the significance level is not stated we choose 5%
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Ho: x = 80
Ha: x > 80
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This is a one-tailed test and we can use Normal distribution z-values since the sample size > 30 and the population is very large compared to sample
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standard error = 10 / square root(40) = 1.5811
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z-value test statistic = (84-80) / 1.5811 = 2.5299 approximately 2.53
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At a 5% significance level, the critical value for a one tailed test is found from the table of z-scores to be 1.645. Since the test statistic is > critical value, we reject the null hypothesis.
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This means either a rare event has occurred or this years batch
is better than previous batches'
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