The school head observes an increase of internet expenditures of learners for months already with a standard deviation of 15 pesos. How many learners must be sampled in order to be 99% confident that...

The school head observes an increase of internet expenditures of learners for months already with a standard deviation of 15 pesos. How many learners must be sampled in order to be 99% confident that the amount spent on internet expenditures will be within P 2.00 of the true mean?