How many ways, can the letters of the word 'QUANTITATIVE' be arranged, so that all T are together?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 907200
1. Count the Frequency of Each Letter
First, let's identify the letters in 'QUANTITATIVE':
- Q: 1
- U: 1
- A: 2
- N: 1
- T: 3
- I: 2
- V: 1
- E: 1
- Total Letters: 12
2. Group the Required Letters
Since all 'T's must be together, we treat the three 'T's as a single block or unit: {TTT}.
Now, we count the total number of units to be arranged:
- The block {TTT}: 1 unit
- Remaining letters: Q(1), U(1), A(2), N(1), I(2), V(1), E(1) = 9 units
- Total Units to arrange: $1 + 9 = 10$ units
3. Calculate the Permutations
The number of ways to arrange these 10 units, accounting for the repeating letters (A appears 2 times and I appears 2 times), is given by the formula:
$\text{Arrangements} = \frac{n!}{p! \cdot q!}$
Where $n$ is the total units, and $p, q$ are the frequencies of repeating units.
$\text{Arrangements} = \frac{10!}{2! \cdot 2!}$
$\text{Arrangements} = \frac{3,628,800}{2 \cdot 2}$
$\text{Arrangements} = \frac{3,628,800}{4} = 907,200$