A telecom company has decided to come up with new sim cards. It got th...
Since the first 4 digits are fixed, all the arrangement and selection is to be done for the next 6 digits.
Now, we can select the 6 digits from all 10 digits, without repetition in 10c6 ways.
Once, we select any set of 6 numbers, there is only one arrangement in which they appear in ascending order. So, for each possible selection, the number of ways = 1.
Hence, the total number of ways of selecting 10-digit numbers =
10C
6 × 1 =
10C
6 =
10C
4 =
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A telecom company has decided to come up with new sim cards. It got th...
Problem Analysis:
- The telecom company has to assign ten-digit numbers to its customers.
- The numbers should start with 7809, and the remaining 6 digits can be selected from all 10 digits without repetition.
- The selected digits should appear in ascending order in the sim card number.
- We need to find the maximum number of sim card numbers the company can come up with.
Solution:
To find the maximum number of sim card numbers, we need to consider the constraints and find the number of possible combinations.
Step 1: Selecting the remaining 6 digits
- The remaining 6 digits can be selected from all 10 digits without repetition.
- This can be done using combination formula: C(n, r) = n! / (r! * (n-r)!)
- In this case, n = 10 (total number of digits) and r = 6 (number of digits to be selected)
- So, C(10, 6) = 10! / (6! * (10-6)!)
= 10! / (6! * 4!)
Step 2: Arranging the selected digits in ascending order
- Once the 6 digits are selected, we need to arrange them in ascending order.
- The order of the digits matters, so we need to use permutation formula: P(n, r) = n! / (n-r)!
- In this case, n = 6 (number of digits selected) and r = 6 (number of digits to be arranged)
- So, P(6, 6) = 6! / (6-6)!
= 6! / 0!
= 6! / 1
= 6!
Step 3: Multiplying the combinations and permutations
- The number of possible combinations of selecting 6 digits from 10 is C(10, 6) = 10! / (6! * 4!)
- The number of possible permutations of arranging the selected 6 digits in ascending order is P(6, 6) = 6!
- To get the maximum number of sim card numbers, we need to multiply these two values.
- Max number of sim card numbers = C(10, 6) * P(6, 6)
= (10! / (6! * 4!)) * 6!
Calculating the Answer:
- Using the formula, we can calculate the maximum number of sim card numbers.
- Max number of sim card numbers = (10! / (6! * 4!)) * 6!
= (10 * 9 * 8 * 7) * (6 * 5 * 4 * 3 * 2 * 1)
= 210 * 720
= 151,200
Conclusion:
- The maximum number of sim card numbers the company can come up with is 151,200.
- The correct answer is option 'A' (210).
A telecom company has decided to come up with new sim cards. It got th...
Since the first 4 digits are fixed, all the arrangement and selection is to be done for the next 6 digits.
Now, we can select the 6 digits from all 10 digits, without repetition in 10c6 ways.
Once, we select any set of 6 numbers, there is only one arrangement in which they appear in ascending order. So, for each possible selection, the number of ways = 1.
Hence, the total number of ways of selecting 10-digit numbers =
10C
6 × 1 =
10C
6 =
10C
4 =
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