Each of 8 identical balls is to be placed in the squares shown in the figures given in a horizontal direction such that one horizontal row contains 6 balls and the other horizontal row contains 2 balls. In how many maximum different ways can this be done?

examrobotsa's picture
Q: 128 (IAS/2006)
Each of 8 identical balls is to be placed in the squares shown in the figures given in a horizontal direction such that one horizontal row contains 6 balls and the other horizontal row contains 2 balls. In how many maximum different ways can this be done?

question_subject: 

Logic/Reasoning

question_exam: 

IAS

stats: 

0,2,4,2,2,1,1

keywords: 

{'many maximum different ways': [0, 0, 3, 0], 'identical balls': [0, 0, 3, 0], 'squares': [0, 0, 1, 0], 'balls': [0, 1, 1, 0], 'other horizontal row': [0, 0, 2, 0], 'horizontal row': [0, 0, 2, 0], 'horizontal direction': [0, 0, 2, 2], 'figures': [0, 0, 1, 1]}

The question is about placing 8 identical balls in two horizontal rows, one with 6 balls and the other with 2 balls.

Option 1 suggests 38 ways to do this. This seems to be the correct answer. By a basic permutation rule "n choose r", which is used to find the number of ways to choose r objects from a set of n objects without considering the order, there can be 8 choose 6 (since six balls are placed in one row) ways and that equals to 28 ways and 8 choose 2 (since two balls are placed in another row) ways and that equals to 28 ways too. Adding them up, we get a total of 56 ways, which contradicts with option 1.

Option 2 suggests 28 ways, which is the number of ways just considered for each row individually rather than the combined placements.

Option 3 suggests 16 ways, and option 4 suggests 14 ways. These two, however, don`t appear to align with the known combinations and numerical logic.

Alert - correct answer should be 56. In the given information, there seems to be a miscalculation or misunderstanding in calculating combinations. The correct number of ways should be 56 (28