A work  sampling  study  is to  be made of a typist  pool. It is  left that  typists are idle  30 % of the  time. How many observations  should  be made  in order  to  have 395.5%  confidence so that  so that  the accuracy  within +    4%.

Solution

Number  of observation required for  work  sampling study=

             N = c² pq / E₂

 Where c  =  constant  depending  on confidence level

 P =  percentage of iding q  percentage of activity  E = absolute error

 C= 2  for  95.5%  confidence level  p = 0.3 , q = 1- p = 0.7, E = 4 % = 0.04

  N =  4X 0.3X 0.7 / 0.04 ²= 0.84 /0.0016= 525