(iv)Three students are chosen at random.Find the probability that exactly 1 is studying Music and exactly 2 are boys. (iv)随机选择三个学生。求正好 1 个在学习音乐,正好 2 个是男生的概率。 qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad
(b)Find the total number of different arrangements of the 8 letters in the word TOMORROW that have an R at the beginning and an R at the end,and in which the three Os are not all together. (b)查找单词 TOMORROW 中开头有 R,结尾有 R 的 8 个不同排列的字母的总数,其中三个 O 并不都在一起。 qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad qquad\qquad