If the estimated population standard deviation based on previous studies is $20, and the acceptable error is plus or minus $5, and the z-value for a 95 percent level of confidence is 1.96, the needed sample size is approximately:

If the estimated population standard deviation based on previous studies is $20, and the acceptable error is plus or minus $5, and the z-value for a 95 percent level of confidence is 1.96, the needed sample size is approximately:



a.

48

b.

210

c.

62

d.

153

e.

196



Answer: C


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