Alma is estimating the proportion of students in her school district who, in the past month. From a random sample of 50 students, she found that 32 students read at least 1 book last month. Assuming all conditions for inference are met, which of the following defines a 90 percent confidence interval for the proportion of all students in her district who read at least 1 book last month?
a. 32 + 1.645,8908.
b. 32 + 1.9620.
c. 0.64 + 1.282.
d. 0.64 + 1.645.
e. 0.64 + 1.96.