Question

Determine the minimum sample size required when you want to be 99% confident that the sample mean is within 0.50 units of the population mean. Assume a population standard deviation of 1.4 in a normally distributed population.

53

52

30

31

Answer 1

Solution :

Given that,

standard deviation = = 1.4

margin of error = E = 0.50

At 99% confidence level the z is ,

   = 1 - 99% = 1 - 0.99 = 0.01

/ 2 = 0.01 / 2 = 0.005

Z/2 = Z0.005 = 2.576

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

= ((2.576 *1.4 ) / 0.50)2

= 52

Minimum Sample size = 52

Option 2nd is correct