Latest Infosys Aptitude Question SOLUTION: Q. How many 4 digit number are their which have exactly 3 distinct digits

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Q. How many 4 digit number are their which have exactly 3 distinct digits

Asked In Infosys Gangatharan (10 years ago)

Solved jai prakash gupta Read Solution (15)

Is this Puzzle helpful?   (15)   (4) Submit Your Solution Number System

Read Solution (15) :

jai prakash gupta  (10 years ago)

0,1,2,3,4,5,6,7,8,9,
not started with 0
in first position= we can arrange in 9 way
2nd position = arrange in 9 way
3rd position= arrange in 8 way
4th position to make only 3 digit different we have only three number left to arrange
9*9*8*3=1944
is it right?

Is this solution Helpfull? Yes (37) | No (13)  

ANSHUL KUMAR  (10 years ago)

answer is 3888

9*9*8*6=3888

all of u are wrong

Is this solution Helpfull? Yes (17) | No (7)  

nalini varshney  (10 years ago)

0,1,2,3,4,5,6,7,8,9,
not started with 0
in first position= we can arrange in 9 way
2nd position = arrange in 9 way
3rd position= arrange in 8 way
question condition is exactly 3 distinct sigits so
4th position= arrange in 7 way
9*9*8*7=4536
is it ri8 ?

Is this solution Helpfull? Yes (17) | No (3)  

anusha  (10 years ago)

1st position in 9 ways
2nd postion z also in 9 ways
3rd postion z in 8 ways
but for 4th position in 10 ways
(he gave exactly 3 distnct digits 4th digit may r may not be same dat means in 0 ways we can select the 4th digit)
ans=9*9*8*10

Is this solution Helpfull? Yes (13) | No (3)  

HARSHAL  (10 years ago)

1,2,3,4,5,6,7,8,9,0
not started with 0
in first position= 9!
2nd position =9!
3rd position=8!
4th position=3
a number must be chosen from used digits, to make only three distinct digits
9!*9!*8!*7!

Is this solution Helpfull? Yes (2) | No (7)  

SURAJ TIWARY  (10 years ago)

10c3= 120 - of ways to choose 3 distinct digits out of 10;
3c1= 3 - of ways to choose which digit will be represented twice;
4!/2!= 12 - of permutation of digits aabc;

10c3*3c1*4!/2!=4320

Is this solution Helpfull? Yes (2) | No (2)  

Abhishek kumar roy  (10 years ago)

Case I:
The repeated digit is the unit's digit.
So, the 1st, 2nd and 3rd digits can be selected in 9 x 9 x 8 ways, respectively.
Now the 4th digit (unit's digit) can be either equal to the 1st, 2nd or 3rd digit.
Thus, in all we have:
9x9x8x3

Case II:
The repeated digit is the ten's digit.
So, the 1st, 2nd and 4th digits can be selected in 9 x 9 x 8 ways, respectively.
Now the 3rd digit (ten's digit) can be either equal to the 1st or 2nd digit.
Thus, in all we have:
9x9x2x8

Case III:
The repeated digit is the hundred's digit.
So, the 1st, 3rd and 4th digits can be selected in 9 x 9 x 8 ways, respectively.
Now the 2nd digit (hundred's digit) is equal to the 1st digit.
Thus, in all we have:
9x1x9x8

In totality, we have 9x9x8(3+2+1) = 9x9x8x6 = 3888

Hope this helps.

Is this solution Helpfull? Yes (2) | No (1)  

T G  (10 years ago)

Sorry @Jai...u r right... I hv msd this part that 3 distinct digit there are ....

Is this solution Helpfull? Yes (1) | No (4)  

shashank sharma  (10 years ago)

i got call for banglore venue 25 jan may i go to for delhi venue 25 jan

Is this solution Helpfull? Yes (1) | No (15)  

swapnika  (10 years ago)

3888 is ans

Is this solution Helpfull? Yes (1) | No   

nandish  (10 years ago)

first combinarion of 3 numbers,then make permutation of 3p3 and is equal to 6.
then make 3 set of 6 numbers.to each number of each set add one of three given numbers with different arrangements.that makes totally 24+24+24=72.
suppose numbers are 1,2,3.number should be of these numbers.meaning no 4,5,6,....9 in numbers.one number will repeat in each number.

Is this solution Helpfull? Yes | No (4)  

T G  (10 years ago)

1,2,3,4,5,6,7,8,9,0
not started with 0
in first position= 9!
2nd position =9!
3rd position=8!
4th position=7!
9!*9!*8!*7!
is it right?

Is this solution Helpfull? Yes | No (12)  

durga  (10 years ago)

ANSHUL KUMAR

can u pls explain it with explanation.......

Is this solution Helpfull? Yes | No (2)  

Debabrata Nayak  (10 years ago)

ans is 6480=9*10*9*8

Is this solution Helpfull? Yes | No (2)  

ragu  (5 years ago)

ans is=8*9*9*9=5832

Is this solution Helpfull? Yes | No (1)  

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