It is given that the population follows normal distribution with variance 9cm^2.

Question

It is given that the population follows normal distribution with variance 9cm^2. What it the smallest sample size required to provide a 95% confidence interval for a mean, if k important that the interval be no longer than 1 cm^2? A principal at a certain school claims that the students in his school are above average intelligence. A random sample of thirty students IQ scores have a mean score of 112. Is there sufficient evidence to support the principal's claim? The mean population IQ is 100 with a standard deviation of 1.5. Six students received the following percentage of marks in two subjects, Mathematics and English. Calculate the correlation coefficient of above data.

Explanation / Answer

(2)

= 9 = 3 cm, E = 1/2 = 0.5 cm

z- score for 95% confidence is z = 1.96

N = (z * /E)^2 = (1.96 * 3/0.5)^2 = 138.30

Minimum sample size = 139

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