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Question 53

Two families with three members each and one family with four members are to be seated in a row. In how many ways can they be seated so that the same family members are not separated?

We have three distinct families: the first family has three members, the second family also has three members, and the third family has four members. The condition “the same family members are not separated” means that every family must sit together as a single block.

So, we first treat each family as one unit or “block.” Now we effectively have only three blocks to arrange in a row.

The number of ways to arrange these three blocks is given by the factorial of the number of blocks. Hence, using the formula for permutations $$n!$$, with $$n = 3$$, we get

$$3!$$

Next, we must consider the internal arrangements within each block.

For the two families that contain three members each, the members can be permuted among themselves independently. The number of ways to arrange the three members of a single family is

$$3!$$

Since there are two such families, the combined number of internal arrangements for these two families is

$$3! \times 3! = (3!)^2$$

Now, for the family that has four members, the members can be arranged among themselves in

$$4!$$

ways.

Because all these internal arrangements happen independently of the arrangement of the blocks, we multiply every individual count together. Hence, the total number of seating arrangements is

$$ \underbrace{3!}_{\text{arrangements of blocks}} \times \underbrace{3!}_{\text{first 3-member family}} \times \underbrace{3!}_{\text{second 3-member family}} \times \underbrace{4!}_{\text{4-member family}} = (3!)^3 \cdot 4! $$

Therefore, the total number of ways is $$(3!)^3 \cdot (4!)$$.

Hence, the correct answer is Option B.

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