How many business students must be randomly selected to estimate the mean monthly earnings of business students at one college? We want 95% confidence that the sample mean is within $135 of the population mean, and the population standard deviation is known to be $538.

Respuesta :

Answer: There are 61 business students must be randomly selected to estimate the mean monthly earnings of business students at one college.

Step-by-step explanation:

Since we have given that

mean = $135

Standard deviation = $538

At 95% level of confidence, z = 1.96

So, we get that

[tex]\bar{x}=z\dfrac{\sigma}{\sqrt{n}}\\135=1.96\times \dfrac{538}{\sqrt{n}}\\\\\dfrac{135}{1.96}=\dfrac{538}{\sqrt{n}}\\\\68.87=\dfrac{538}{\sqrt{n}}\\\\\sqrt{n}=\dfrac{538}{68.87}\\\\\sqrt{n}=7.8\\\\n=7.8^2\approx 61[/tex]

Hence, there are 61 business students must be randomly selected to estimate the mean monthly earnings of business students at one college.

The number of business students must be randomly selected is 61 students.

standard deviation (σ) = 538, sample size (n), margin of error (E) = 135

Confidence (C) = 95% = 0.95

α = 1 - C = 1 - 0.95 = 0.05

α/2 = 0.025

The z score of α/2 is the same as the z score of 0.475 (0.5 - 0.025) which is equal to 1.96.

[tex]E=z_\frac{\alpha}{2} *\frac{\sigma}{\sqrt{n} } 135\\\\135=1.96*\frac{538}{\sqrt{n} }\\\\n=61[/tex]

The number of business students must be randomly selected is 61 students.

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