A manufacturer uses several machines on its production line (all the same type of machine), each of which sometimes produces defective items. It is known that a machine of this type usually produces defective items about 10% of the time. To assess the condition of a particular machine, the foreman wants to estimate the proportion of all items produced by that machine which are defective, using a 90% confidence interval.
How many items should be sampled to produce the desired confidence interval, limiting the margin of error to 2.5 percentage points? Enter a whole number.
