In how many ways can 7 identical erasers be distributed among 4 kids in such a way that each kid gets at least one eraser but nobody gets more than 3 erasers?
  • a)
    16
  • b)
    20
  • c)
    14
  • d)
    15
Correct answer is option 'A'. Can you explain this answer?

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Answers

Pathways Academy
Feb 06, 2021
We have been given that a + b + c + d = 7
Total ways of distributing 7 things among 4 people so that each one gets at least one = n-1Cr-1 = 6C3 = 20 Now we need to subtract the cases where any one person got more than 3 erasers. Any person cannot get more than 4 erasers since each child has to get at least 1. Any of the 4 childs can get 4 erasers. Thus, there are 4 cases. On subtracting these cases from the total cases we get the required answer. Hence, the required value is 20 - 4 = 16

We have been given that a + b + c + d = 7Total ways of distributing 7 things among 4 people so that each one gets at least one = n-1Cr-1 = 6C3 = 20 Now we need to subtract the cases where any one person got more than 3 erasers. Any person cannot get more than 4 erasers since each child has to get at least 1. Any of the 4 childs can get 4 erasers. Thus, there are 4 cases. On subtracting these cases from the total cases we get the required answer. Hence, the required value is 20 - 4 = 16
We have been given that a + b + c + d = 7Total ways of distributing 7 things among 4 people so that each one gets at least one = n-1Cr-1 = 6C3 = 20 Now we need to subtract the cases where any one person got more than 3 erasers. Any person cannot get more than 4 erasers since each child has to get at least 1. Any of the 4 childs can get 4 erasers. Thus, there are 4 cases. On subtracting these cases from the total cases we get the required answer. Hence, the required value is 20 - 4 = 16