<image>To understand the extracurricular reading habits of eighth-grade students, a study randomly surveyed 25 students in this grade. The data sample of their extracurricular reading time (denoted as t, in hours) last weekend is shown in the pie chart below. 
(1) What percentage of students read for 4 hours? How many students is that? 
(2) Determine the median and mode of this sample, and calculate the mean.