A random sample of 64 students at a university showed an average age of 20 years and a sample standard deviation of 4 years. The 90% confidence interval for the true average age of all students in the university is

The 90%  confidence level is  

Step-by-step explanation:

From the question we are told that

     The sample size is  

     The mean age is  

      The standard deviation  is  

Generally  the degree of freedom for this data set is mathematically represented as

substituting values

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

         10 %  

Now  

Since we are considering a on tail experiment

The  critical value for half of  this significance level at the calculated  degree of freedom is obtained from the critical value table as

   The margin for error is mathematically represented as

substituting values  

he 90% confidence interval for the true average age of all students in the university is evaluated as follows

substituting values  

option c) graph of line going through 1, 4 and 3, 10

step-by-step explanation:

let y equal to margo's coin collection

let x equal to number of years

at the begining x=0, y=1 → point=(x,y)→point=(0,1)

she adds 3 coins per year, then y=1+3x

at x=1, y=1+3(1)=1+3→y=4→point=(x,y)→point=(1,4)

at x=3, y=1+3(3)=1+9→y=10→point=(x,y)→point=(3,10)

the graph of line going through (1, 4) and (3, 10), then the option c is the correct.

c > -10.55

step-by-step explanation: