Aprogrammer plans to develop a new software system. in planning for the operating system he will use, he needs to estimate the percentage of computers that use a new operating systems. how many computers must be surveyed in order to be 90% confident that his estimate is in error by no more than four percentage points? a) assume that nothing is known about the percentage of computers with new operating systems. n = ? b) assume that a recent survey suggests that 99% of computers use a new operating system. n = ?

a) 423  b) 17

Step-by-step explanation:

As per given , we have

E=4% = 0.04

Confidence level : 90%

The critical value for 90% confidence interval : z*=1.645

a) When the prior estimate of the population proportion is unknown , then the formula to find the sample size is given by :-

, where E = margin of error.

z* = Critical value.

Required sample size :  (Substitute the given values in the formula)

i.e. n= 423

b) When the prior estimate of the population proportion is known , then the formula to find the sample size is given by :-

, where p = Population proportion from prior study.

E = margin of error.

z* = Critical value.

here p= 0.99

     (Substitute the given values in the formula)

i.e. n= 17

histogram or dot plot?

step-by-step explanation: