Answer:
Confidence interval = ( 0.7991, 0.8647 )
Step-by-step explanation:
Sample size = n = 351
number of successes = X = 292
Sample proportion = P = 
                                      =  
                                      = 0.831908831
confidence interval = 90%
Critical Z value  = 1.6449   [by using excel]
Confidence interval = P ± Z 
Where P = Sample proportion
            Z = critical value
            n = sample size
Confidence interval =  0.831908831 ± 1.6449 
                                 = 0.831908831 ± 1.6449 × 0.0200
                                 = 0.831908831 ± 0.032898
  Lower limit             = 0.831908831 - 0.032898 = 0.7991
Upper limit               = 0.831908831 + 0.032898 = 0.8647
Confidence interval = ( 0.7991, 0.8647 )