हिंदी

The number of 5-digit telephone numbers having atleast one of their digits repeated is ______.

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प्रश्न

The number of 5-digit telephone numbers having atleast one of their digits repeated is ______.

विकल्प

  • 90,000

  • 10,000

  • 30,240

  • 69,760

MCQ
रिक्त स्थान भरें
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उत्तर

The number of 5-digit telephone numbers having atleast one of their digits repeated is 69,760.

Explanation:

Total number of 5-digit telephone number if all the digits are repeated = (10)5   ......[∵ Digits are from 0 to 9]

If digits are not repeated, then 5-digit telephones, can be formed in 10P5 ways

∴ Required number of ways = (10)5 – 10P5

= `100000 - (10!)/((10 - 5)!)`

= `100000 - (10 xx 9 xx 8 xx 7 xx 6 xx 5!)/(5!)`

= 100000 – 30240

= 69760

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अध्याय 7: Permutations and Combinations - Exercise [पृष्ठ १२५]

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एनसीईआरटी एक्झांप्लर Mathematics Exemplar [English] Class 11
अध्याय 7 Permutations and Combinations
Exercise | Q 36 | पृष्ठ १२५

वीडियो ट्यूटोरियलVIEW ALL [1]

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