help with math hw

Question

People were polled on how many books they read the previous year. Initial survey results indicate that

sequals=12.8

books. Complete parts ​(a) through ​(d) below.

Click the icon to view a partial table of critical values.

​(a) How many subjects are needed to estimate the mean number of books read the previous year within

six

books with

95​%

​confidence?

This

95%

confidence level requires

_____

subjects. ​(Round up to the nearest​ subject.)

Answer 1

The desired margin of error is 6 books.

Margin of error is defined as z* standard deviation/sample size

For 95% confidence z* (z critical) = 1.96

So we want 1.96 * standard deviation/sample size <= 6

This problem cannot be completed with the standard deviation being provided.