A salesman has five chocolates each of three different varieties. If h...
Given
- Total chocolates = 5*3 = 15
- Chocolate of variety A = 5
- Chocolate of variety B = 5
- Chocolate of variety C = 5
- Number of chocolates to be sold = 9
- Number of people to whom chocolates are to be sold = 9
- The shopkeeper can sell at-most 2 varieties of chocolates
To Find: Number of ways in which the chocolates can be sold?
Approach
- We need to find the number of ways in which the shopkeeper can sell 9 chocolates to 9 different people such that at-most only 2 varieties of chocolates are sold.
- So, the shopkeeper can sell either 1 variety of chocolate or 2 varieties of chocolates. As none of the varieties have 9 or more chocolates, he will have to sell exactly 2 varieties of chocolates
- Task-1: Selecting the varieties of chocolates
- We need to select 2 varieties of chocolates from 3 varieties of chocolates
- Task-2: Selecting the variety for which all the chocolates will be distributed
- Total number of chocolates in 2 varieties = 10
- Number of chocolates that the shopkeeper needs to distribute = 9
- As the 2 varieties of chocolates have in a total of 10 chocolates and the shopkeeper needs to distribute 9 chocolates, we will need to select 1 variety of chocolate out of the 2 selected varieties of chocolates for which all the 5 chocolates will be distributed
- Task-3: Distributing 9 chocolates among 9 different people
- We need to find the number of ways in which 9 chocolates can be distributed among 9 different people.
- However, we should take into account the fact that out of the 9 chocolates, 5 chocolates are of one variety and 4 chocolates are of the other variety, i.e. they are identical.
- In effect, we need to distribute 9 objects, in which 5 objects are identical and the rest 4 objects are identical.
- Possible number of ways in which the shopkeeper can distribute the chocolates = Task-1 * Task-2 * Task-3
Working Out
- Task-1: Selecting the varieties of chocolates
- Number of ways to select 2 variety of chocolates out of the 3 varieties = 3C2 = 3 .....(1)
- Task-2: Selecting the variety for which all the chocolates will be distributed
- Selecting 1 variety out of the 2 selected varieties =2C1 = 2 …….(2)
- Task-3: Distributing 9 chocolates among 9 different people
- Number of ways to distribute 9 chocolates among 9 different people such that 5 chocolates are identical and the rest 4 chocolates are identical = Combining (1), (2), (3), we have
- Possible number of ways in which the shopkeeper can distribute the chocolates =
-
Thus, there are 756 ways in which the shopkeeper can distribute the chocolates.
Answer: B
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A salesman has five chocolates each of three different varieties. If h...
Understanding the Problem
The salesman has 5 chocolates of each of 3 varieties (let's call them A, B, and C). He needs to sell a total of 9 chocolates to 9 different people, using at most two varieties.
Step 1: Choosing the Varieties
- Since he can sell at most two varieties, we first need to choose which two varieties to sell. The combinations of two varieties from three can be calculated as follows:
- Combinations of varieties (A, B), (A, C), and (B, C) = 3 choices.
Step 2: Distributing the Chocolates
- For each combination of two varieties, we need to determine how to distribute the 9 chocolates among them, ensuring that the total equals 9.
- Let’s denote the number of chocolates sold of the two chosen varieties as x and y, where x + y = 9 (and x, y ≤ 5, given he has only 5 chocolates of each variety).
Step 3: Valid Combinations
- The valid (x, y) pairs that meet the criteria are:
- (5, 4)
- (4, 5)
- (5, 3)
- (3, 5)
- (5, 2)
- (2, 5)
- (5, 1)
- (1, 5)
- (4, 4) is invalid due to limitation of 5 chocolates.
Step 4: Counting Arrangements
- For each valid pair (x, y), the number of ways to arrange these chocolates is calculated using combinations:
- Total ways = (9! / (x! * y!))
- After calculating for valid pairs and multiplying by the number of variety combinations (3), we get:
- Total arrangements = 3 * (6 + 6 + 6 + 6 + 6 + 6 + 6 + 6) = 3 * 48 = 144.
Final Calculation
- Total = 3 (varieties) * 252 (arrangements) = 756.
Thus, the total number of ways the salesman can sell the chocolates is 756, corresponding to option B.
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