1.

An n-digit numberis a positive number with exactly`n`digits. Ninehundred distinct n-digit numbers are to be formed using only the three digits2, 5, and 7. The smallest value of `n`for whichthis is possible isa.`6`b. `7`c. `8`d. `9`A. 6B. 7C. 8D. 9

Answer» Correct Answer - B
Distinct n - digit numbers which can be formed using digits 2, 5 and 7 are `3^(n)`. We have to find n, so that
`3^(n) ge 900`
`rArr" " 3^(n - 2) ge 100`
`rArr" " n - 2 ge 5`
`rArr" " n ge 7`, so the least value of n is 7.


Discussion

No Comment Found

Related InterviewSolutions