Question

Determine the minimum sample size required when you want to be 95% confident that the sample mean is within 1.2 unites of the population mean. Assume that the population is normally distributed with standard deviation σ = 4.8.

1. The critical value:

1.9600

2. The margin of error:

Incorrect.

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3. The sample size:

62

Answer 1

Solution :

Given that,

standard deviation = = 4.8

margin of error = E = 1.2

At 95% confidence level the z is ,

= 1 - 95% = 1 - 0.95 = 0.05

/ 2 = 0.05 / 2 = 0.025

Z/2 = Z 0.025 = 1.96

Sample size = n = ((Z/2 * ) / E)2

= ((1.96 * 4.8) / 1.2)2

= 61

Sample size = 61