Q16 of 64 Page 122

Find the number of integers greater than 7000 that can be formed with the digits 3, 5, 7, 8 and 9 where no digits are repeated. [Hint: Besides 4-digit integers greater than 7000, five digit integers are always greater than 7000.]

GIVEN:-Digits to be use are 3,5,7,8,9


There should be 4 digits integers greater than 7000


And five digits integers are always greater than 7000


The number of integers is 5P5


For a four-digit integer to be greater than 7000 it must begin with 7,8 or 9.


The number of such integer is 3x4P3


=3x4P3


=3(24) =72


Total no of ways


=120+72


=192


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