A random sample of 16 ATM transactions at the Last National Bank of Flat Rock revealed a mean transaction time of 2.8 minutes with a standard deviation of 1.2 minutes. The width (in minutes) of the 95 percent confidence interval for the true mean transaction time is plus/minus (to three decimal places):

The  width is  

Step-by-step explanation:

From the question we are told that

    The  sample size is  n = 16    

      The mean time is      

     The standard deviation is  

Generally the degree of freedom is mathematically represented as  

=>      

=>    

From the question we are told the confidence level is  95% , hence the level of significance is    

=>  

Generally from the t distribution table the critical value  of   at a degree of freedom of  df = 15 is  

Generally the margin of error is mathematically represented as  

=>    

=>    

Generally the width the confidence 95% confidence interval  

=>    

=>    

the simplified form is

step-by-step explanation:

we want to simplify the expression,

let us change the middle bar to a normal division sign to obtain,

we multiply the first fraction by the reciprocal of the second fraction to obtain,

we factor to obtain,

we cancel the common factors to get,

we simplify to get,

the correct answer is b