In how many different ways can the letters of the word BOOKLET be arra...
Understanding the Problem
To find the number of arrangements of the letters in the word "BOOKLET" where B and T are always together, we can treat B and T as a single unit or block. This reduces the complexity of the arrangement.
Step 1: Treat B and T as a Single Block
- When B and T are together, we can represent them as one block: (BT).
- The letters of the word "BOOKLET" consist of: B, O, O, K, L, E, T.
- By treating (BT) as one letter, we now have the following letters to arrange: (BT), O, O, K, L, E.
Step 2: Count the Total Letters
- The total letters to arrange now are: (BT), O, O, K, L, E.
- This gives us a total of 6 units: (BT), O, O, K, L, E.
Step 3: Calculate Arrangements
- The formula for permutations of n objects where some objects are identical is given by: n! / (n1! * n2! * ... * nk!).
- Here, we have:
- n = 6 (total units: (BT), O, O, K, L, E).
- O appears twice (2 identical O's).
- Therefore, the number of arrangements is calculated as follows:
Number of arrangements = 6! / 2! = 720 / 2 = 360.
Step 4: Account for the Arrangement of B and T
- Within the block (BT), B and T can also be arranged in 2 ways: BT or TB.
- Therefore, the total arrangements considering B and T can be swapped are:
Total arrangements = 360 * 2 = 720.
Final Answer
Thus, the total number of arrangements of the letters in the word "BOOKLET," where B and T are always together, is 720.
The correct option is B.