Answer these questions based on the following informations
After completing his MBA, Zafar shifted to a new flat where he bought a new bookself and a set of 7 novels. The names of these novels, In the chronoligical order, are A,B,C,D,E, F and G
He wants to keep the novels in his bookshelf such that the first two novels of the series are always kept together, find the number of ways in which he can arrange all the novels

Options

A. 120
B. 2440
C. 720
D. 1440

Answer

To solve the problem of arranging Zafar's 7 novels (A, B, C, D, E, F, G) such that the first two novels (A and B) are always kept together, we can follow these steps:

### Step-by-Step Solution:

1. **Treat the First Two Novels as One Unit**:
Since A and B must always be together, we can treat them as a single unit or block. Let's denote this block as (AB).

2. **Count the Total Units**:
After treating A and B as one unit, we now have the following units to arrange:
- (AB), C, D, E, F, G
This gives us a total of 6 units to arrange: (AB), C, D, E, F, G.

3. **Calculate the Arrangements of the Units**:
The number of ways to arrange these 6 units is given by the factorial of the number of units:
\[ 6! = 720 \]

4. **Arrange the Novels within the Block**:
Within the block (AB), A and B can be arranged in 2 different ways (AB or BA).

5. **Calculate the Total Arrangements**:
To find the total arrangements, we multiply the arrangements of the units by the arrangements within the block:
\[ \text{Total Arrangements} = 6! \times 2 = 720 \times 2 = 1440 \]

### Final Answer:
The total number of ways Zafar can arrange all the novels such that the first two novels are always kept together is **1440**.

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