What is the minimum sample size required to estimate a population mean with 90% confidence when the desired margin of error is 1.25

Complete Question

What is the minimum sample size required to estimate a population mean with 90% confidence when the desired margin of error is 1.25? The standard deviation in a pre-selected sample is  7.5

The minimum sample size is  

Step-by-step explanation:

From the question  we are told that

 The margin of error is  

   The  standard deviation is  

Given that the confidence level is  90% then the level of significance is mathematically represented as

Next we obtain the critical value of from the normal distribution table  

    The value is  

   The  minimum sample size is mathematically evaluated as

=>        

=>        

1 1/4 hours

step-by-step explanation:

2/4 + 2/4 + 1/4 = 5/4 or 1 1/4

incomplete question. how do you expect anyone to you when you do not post the question in its entirety?