public void BookCalculatesStats()
{
//arrange
var book = new InMemoryBook("");
book.addGrade(89.1);
book.addGrade(90.5);
book.addGrade(77.3);
//act
var result = book.computeStatistics();
//assert
Assert.Equal(85.6, result.Average, 1);
Assert.Equal(90.5, result.High, 1);
Assert.Equal(77.3, result.Low, 1);
}
