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PUNE MCA Exam 2016 Question Paper with answers for online practice

Question : 18 of 50

Marks: +1, -0

Six frogs in which three are greens and three are brown. They are sitting each on its own rock/stone near each other in a line. There is an empty rock/stone between the green and brown frogs as shown below

Green Frog - Green Frog – Green Frog – Empty Rock – Brown Frog - Brown Frog - Brown Frog. Green frogs can only hop to the right. Brown frog can only hop to the left. Frogs can only jump on to a empty rock. A frog can jump over one frog to an empty rock but only ever one. Frogs can’t jump back only forward.

The minimum number of hops required such that

the position of the frogs as belowBrown Frog - Brown Frog - Brown Frog – EmptyRock –Green Frog - Green Frog – Green Frog?

12
16
18
None

Validate

Solution:

Concept:

This is a classic frogs-and-toads puzzle where frogs of one color move only right, the other only left, sliding or jumping over one frog to an empty rock.

Explanation:

For

n

frogs on each side (here

n=3

), the minimum number of moves is given by

n(n+2)

For

n=3

, this is

3 \times (3+2) = 15

The sequence of hops is well-known and yields exactly 15 moves.

Since 15 is not listed among the options (12, 16, 18), the correct choice is "None".

Answer:

15 hops are needed, which is not in the given options.

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