Answer:
The 99% confidence interval would be given (11.448;14.152).
Step-by-step explanation:
1) Important concepts and notation
A confidence interval for a mean "gives us a range of plausible values for the population mean. If a confidence interval does not include a particular value, we can say that it is not likely that the particular value is the true population mean"
 represent the sample deviation
 represent the sample deviation
 represent the sample mean
 represent the sample mean
n =1003 is the sample size selected
Confidence =99% or 0.99
 represent the significance level.
 represent the significance level.
2) Solution to the problem
The confidence interval for the mean would be given by this formula

We can use a z quantile instead of t since the sample size is large enough.
For the 99% confidence interval the value of  and
 and  , with that value we can find the quantile required for the interval in the normal standard distribution.
, with that value we can find the quantile required for the interval in the normal standard distribution.

And replacing into the confidence interval formula we got:


And the 99% confidence interval would be given (11.448;14.152).
We are confident that about 11 to 14 are the number of books that the people had read on the last year on average, at 1% of significance.