Question 1133948
For part A, the point estimate is the observed or sample proportion.

For part B, the margin of error is calculated using the z-score that corresponds to a 90% confidence level which is estimated to be 1.645.  This is multiplied by the sq rt of p-hat, q-hat (observed failures proportion) divided by n

For part C, the margin of error is subtracted from and added to the observed proportion.

For part D, C is the correct interpretation.

*[illustration CI_Solution]