- #1
jinx007
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Please i need help i am not that good in probability and permutation.
The digits of the number 1,2,2,3,6,7,8 can be read to give many 7-digits numbers. Find how many different 7-digit numbers can be made if
1/ There is no restriction on the order of the digits.
2/ The digits 1,3,7(in any order) are next to each other
3/ These 7-digits numbers are even
1/ if no restriction so 7 ! = 5040 ways
2/ so here i treat 1,3,7 as a block and is equal to 1 ! and i add to the remaining and i get 4 ! + 1 ! = 5!
And my answer = 5! x 3
But i am not sure...please check it..and tell me if there is any error
3/ I treat the last block as even so (2,2,6,8)...> 4!
my answer 6 x 5 x 4 x 3 x 2 x 1 x 4! = 17280 ways
ALL WHAT I HAVE DONE, I AM NOT SURE..PLEASE CHECK IT...I HAVE MANY DOUBT...THANKS IN ADVANCE
The digits of the number 1,2,2,3,6,7,8 can be read to give many 7-digits numbers. Find how many different 7-digit numbers can be made if
1/ There is no restriction on the order of the digits.
2/ The digits 1,3,7(in any order) are next to each other
3/ These 7-digits numbers are even
1/ if no restriction so 7 ! = 5040 ways
2/ so here i treat 1,3,7 as a block and is equal to 1 ! and i add to the remaining and i get 4 ! + 1 ! = 5!
And my answer = 5! x 3
But i am not sure...please check it..and tell me if there is any error
3/ I treat the last block as even so (2,2,6,8)...> 4!
my answer 6 x 5 x 4 x 3 x 2 x 1 x 4! = 17280 ways
ALL WHAT I HAVE DONE, I AM NOT SURE..PLEASE CHECK IT...I HAVE MANY DOUBT...THANKS IN ADVANCE