5d = 30 i cant find the answer
2 answers:
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Answer:
2,436 students
Step-by-step explanation:
At a 90% confidence level, the z-score is 1.645 and the confidence interval is given by:
Where s is the standard deviation, and n is the sample size.
If they want the length of their confidence interval to be no greater than 0.2, it must be no further than 0.1 from the mean 'X':
Rounding up to the next whole number, the sample size should be 2,436 students.