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A fifth grade teacher believes that 12% of her students are late for class. If the teacher is right, what is the probability that the proportion of late students in a sample of 538 students would differ from the population proportion by less than 3%? Round your answer to four decimal places.

User JonoJames
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Answer:

Explanation:

Given:

Proportion of students who are late for class in the population: p = 0.12

Sample size: n = 538

Margin of error: E = 0.03

The standard error of the proportion can be calculated using the formula:

SE = sqrt(p*(1-p)/n)

SE = sqrt(0.12*0.88/538)

SE = 0.019

The margin of error corresponds to a z-score at the 97.5th percentile (since we want the probability of the sample proportion being within 3% of the population proportion in either direction, which gives us a two-tailed test with an alpha level of 0.025 on each side). This z-score can be found using a standard normal distribution table or calculator and is approximately 1.96.

The margin of error can also be calculated using the formula:

E = z*(SE)

0.03 = 1.96*(0.019)

To find the probability that the sample proportion differs from the population proportion by less than 3%, we need to find the area under the standard normal distribution curve between the z-scores of -1.96 and 1.96. This area is equivalent to the probability of the sample proportion being within 3% of the population proportion. This probability can be found using a standard normal distribution table or calculator and is approximately 0.8534.

Therefore, the probability that the proportion of late students in a sample of 538 students would differ from the population proportion by less than 3% is 0.8534 or 85.34% (rounded to four decimal places)

User Heikura
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