In a survey of 3474 adults aged 57 through 85​ years, it was found that 88.3​% of them used at least one prescription medication. Complete parts​ (a) through​ (c) below. a. How many of the 3474 subjects used at least one prescription​ medication?

Step-by-step explanation:

(1)  Find alpha (α) = 10%  or 0.10

(2)  Find (α/2) = 5% or 0.05

(3)  Subtract 0.05 from 1.0000 to get 0.9500

So the interval of a 90% confidence interval is from 0.0500 < p < 0.9500

Find zα/2 at 0.9500 from z-score normal distribution table yielding z = 1.65

Using z-values →    -1.65 < z < 1.65

I think your answer would be C I am not sure the way I worked it out says C. I hope this helps you out.