How many students were in this test about economics?

How much do American high school students know about economics? A new report shows that seventy-nine percent of twelfth-graders have at least a basic level of understanding. (29)The results come from testing eleven thousand five hundred students last year in public and private schools.
    (30) In fact, students did better in economics than in history or science. Only forty-seven percent of those tested reached the basic level in history. And fifty-four percent performed at or above the basic level in science.
     This is the first time the federal government has measured economic understanding among high school students. The study was done as part of the National Assessment of Educational Progress, called the Nation’s Report Card.