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A shopping mall has a large basement parking lot with parking slots painted in it along a single row. These slots are quite narrow; a compact car can fit in a single slot but an SUV requires two slots. When a car arrives, the parking attendant guides the car to the first available slot from the beginning of the row into which the car can fit.

For our purpose, cars are numbered according to the order in which they arrive at the lot. For example, the first car to arrive is given a number 1, the second a number 2, and so on. This numbering does not indicate whether a car is a compact or an SUV. The configuration of a parking lot is a sequence of the car numbers in each slot. Each single vacant slot is represented by letter V.

For instance, suppose cars numbered 1 through 5 arrive and park, where cars 1, 3 and 5 are compact cars and 2 and 4 are SUVs. At this point, the parking lot would be described by the sequence 1, 2, 3, 4, 5. If cars 2 and 5 now vacate their slots, the parking lot would now be described as 1, V, V, 3, 4. If a compact car (numbered 6) arrives subsequently followed by an SUV (numbered 7), the parking lot would be described by the sequence 1, 6, V, 3, 4, 7.

Answer the following questions INDEPENDENTLY of each other.

Suppose eight cars have arrived, of which two have left. Also suppose that car 4 is a compact and car 7 is an SUV. Which of the following is a POSSIBLE current configuration of the parking lot?

Solution

✅ Correct Option: 1
Slide 1/2

Understanding the Set:

  1. This is an arrangement set. In this set, there are two types of cars — Compact and SUV — that need to be parked.
  1. A Compact car can fit in a single slot, but an SUV requires two slots.
  1. Cars are numbered according to the order in which they arrive at the lot

(the first car to arrive is numbered 1, and so on).

  1. If there is any vacant slot, we mark it as "V".

Now, after reading the set, you’ll find that there isn’t much information or many clues in the passage.

Thus, we need to solve the set based on the specific requirements of each question.

Solve this by options:

D: 8, 2, 3, V, 5, 7, 6

This means that the missing numbers (i.e. 1 and 4) have left.

There is no situation where 1 and 4 leave but 6 is after 7.

If 6 arrived first, then clearly it should be after 5,

and since 1 and 4 are leaving this in any case does not affect how 6 can be after 7 despite arriving earlier.

This option is not possible

B: 8, 2, 3, V, 6, 5, 7

Here again, 1 and 4 have left.

Once again, there is no situation where 6 can be before 5. (unlesss 4 is an SUV but clearly stated that 4 is a compact car)

A: 8, 2, 3, V, 5, 6, 7

This is feasible.

1 and 4 left, 8 arrived last so fills 1's space.

This is the correct answer

Only option 1 is true where car 4 left after car 5 arrived.

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