There are 4 identical mathematics
books, 2 identic physics books
and 2 identical chemistry books
. How many ways to compile
the eight books on the condition
of the same book are not mutually
adjacent?
A student wrote three papers in mathematics
examinations. Her marks for the two of
papers were 77 and 72 respectively. To
obtain grade A, an average of not less
than 75 marks is required for the three
papers. How many marks must she get
in the third paper to get grade A?