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If n integer taken at random are multiplied together then the probability that the last digit of the product is 2, 4, 6, 8 is ?
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- 2n/5n
- 4n - 2n / 5n
- 4n/5n
- 8n - 4n / 5n
Correct Option: B
If the last digit in the product is to 2, 4, 6, 8 the last digit in all the n number should not be 0 and 5 and the last digit of all number should not be selected exclusively from the set of number {1, 3, 7, 9}
∴ Favourable number of cases
= 8n - 4n
But generally the last digit can be one of 0, 1, 2, 3, .... 9.
Hence, the total number of ways = 10n
Hence, the required probability
= 8n - 4n / 10n
= 4n - 2n / 5n
