Latest TCS Aptitude Question SOLUTION: how many 4-digit odd no.can b formd,such dat evry 3 in d no.is folowd by a 6????? a.108 b.2592 c.2696 d.2700

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(#M40011086) TCS question Keep an EYE

how many 4-digit odd no.can b formd,such dat evry 3 in d no.is folowd by a 6?????
a.108
b.2592
c.2696
d.2700

Asked In TCS deepak gupta (12 years ago)

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Sanket Kumar  (12 years ago)

Answer comes out to be close to 108.
Since, it is an odd number, last digit cannot be 6.
So, the possibility of 3 at TEN's and UNIT's position is ruled out.Hence, 3 could occupy either THOUSAND's place or HUNDRED's place.

The possible number outcomes are as follows :
1) 36xx : Now there are 50 odd nos between 601 and 699. hence, total numbers in this case = 50
2) x36x : here, for every Thousand th place we need to evaluate for digits
(1-9),
Eg, 1361-1369 = 5 numbers and so on
9361-9369 = 5 numbers
In this case overall, v get 45 numbers.
So answer is closer to 108 rather than other options.Please suggest a better answer asap.

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Sanket Kumar  (12 years ago)

@KUMAR CHANDRAJEET Just had a small doubt.Actually, second contition u considered cannot be valid.As, 6 immediately follows a 3 in the number.

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Souparna Roy  (12 years ago)

3 Cases:-
1st->no. of odd words formed by the arrangement(36--)=1*1*9*4=36
2nd->no. of odd words formed by the arrangement(-36-)=9*1*1*4=36
3rd->no. of odd words formed by the arrangement without taking 3,6 pair (----)= 8*9*9*4=2592.
no other cases r possible because 6 cannot be placed at unit place.
therefore total no. of words=36+36+2592=2664.(ans)

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kumar chandrajeet  (12 years ago)

3 will not come at unit place so let us see the possible combination
possible digits
3 6 - odd, 9*4=36 word
3 - 6 odd, 10*4=40 word
- 3 6 odd, 9*4=36 word
- - - odd, 8*9*9*4=2592 word
so toatal word =36+40+36+2592=2704 ans

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