Answer:
The  90%  confidence interval for population mean is   
Step-by-step explanation:
From the question we are told that 
    The sample mean is  
     The confidence level is  
      The sample size is  
      The standard deviation 
Now given that the confidence level is  0.90 the  level of significance is mathematically evaluated as
        
        
Next we obtain the critical value of   from the standardized normal distribution table. The values is
  from the standardized normal distribution table. The values is  
The  reason we are obtaining critical values for  instead of  that of
  instead of  that of   is because
  is because  represents the area under the normal curve where the confidence level 1 -
  represents the area under the normal curve where the confidence level 1 -  (90%)  did not cover which include both the left and right tail while
 (90%)  did not cover which include both the left and right tail while  is just considering the area of one tail which is what we required calculate the margin of error
  is just considering the area of one tail which is what we required calculate the margin of error 
   Generally the margin of error is mathematically evaluated as 
         
substituting values 
          
          
The  90%  confidence level interval is mathematically represented as 
       
substituting values 
      
     
      