Mathematics 9709 · AS & A Level · Permutations and combinations
Permutations and combinations — practice question
The eight digits $1, 2, 2, 3, 4, 4, 4, 5$ are placed in one row.
(a)[1]
How many distinct arrangements can be made from these 8 digits?
(b)[4]
Find the number of distinct arrangements of the 8 digits in which there is a 2 at the beginning, a 2 at the end and the three 4s are not all together.
(c)[5]
Find the probability that all three digits are different.
Worked solution & mark scheme
This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Accurate evaluation of permutations using $\frac{8!}{2!3!}$.” …