The proportion of junior executives leaving large manufactur

The proportion of junior executives leaving large manufacturing companies within three years is to be estimated within 4 percent. The 0.95 degree of confidence is to be used. A study conducted several years ago revealed that the percent of junior executives leaving within three years was 25. To update this study, the files of how many junior executives should be studied?

Solution

= POPULATION PROPORTION 25 (25% - assumption)
B = SPECIFIED BOUND ON THE ERROR 0.04
Level of Confidence 95
\'z critical value\' from Look-up Table for 95% 1.96
or Excel NORMSINV(probability) = NORMSINV ( 0.5*( 1 - 95 / 100 )))
Returns \'z critical value\' from the inverse of the standard normal cumulative distribution. The distribution has a mean of zero and a standard deviation of one.

significant digits 3

B = \'z critical value\' * SQRT [ * (1 - )/n]
Algebraically solve for SAMPLE SIZE n :
n = * (1 - ) * [ \'z critical value\' / B ]^2 = 0.25 * (1 - 0.25) * [ 1.96 / 0.03 ]^2
n = (z/E)^2*(p*q)
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n = (1.96/0.03)^2*0.25*0.79 =842.58~843