Latest Elitmus Aptitude Question SOLUTION: yr anyone solve the question first digit is same as last digit and middle one are all same abbbbbba i dint remember completely ,,maine ye pehle bhi khi pda hai but yr dhan nhi aa r

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(#M40030491) ELITMUS Numerical Ability question Keep an EYE

yr anyone solve the question first digit is same as last digit and middle one are all same abbbbbba i dint remember completely ,,maine ye pehle bhi khi pda hai but yr dhan nhi aa rha...is there is anyone who solve this question?

Asked In Elitmus ankit chauhan (10 years ago)

Unsolved Read Solution (12)

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tri  (10 years ago)

a and b can take 9*8 values.. 72

rest as above so 24 / 72 = 12/36

Is this solution Helpfull? Yes (8) | No   

tri  (10 years ago)

abbbbbba divisible by 3.. aisa tha shayad..
(2*a + 6*b )/3 ..
a and b can take distinct values from 1 to 9 ...

6b is divisible by 3 so "a" can take 3, 6, 9 as values

if a=3 b can be any of the other 8
same for a= 6
and b= 9

8+8+8= 24

Is this solution Helpfull? Yes (4) | No   

kirti agarwal  (10 years ago)

question was like: what is the probability that a 8 digit number where digits of the number is any two number from 1 to 9, is divisible by 3.
number is of form abbbbbba.

1:3/36
2:9/36
3:8/36
4:12/36

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Richa  (10 years ago)

answers me 4/36 option bhi tha ..

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tri  (10 years ago)

ankit .. I left the question.. 12/36 bhi tha kya option mein??????

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ayush srivastava  (9 years ago)

@tri,kirti,richa
home A 9616157559

Answer to question:
what is the probability that a 8 digit number where digits of the number is any two number from 1 to 9, is divisible by 3.
number is of form abbbbbba.

i have assumed "a is not equal to b"

we know 2a+6*b is divisible by 3
(2a+6*b)%3=0 => (a+3*b)%3=0

a and b can have value from only 1-9
so, possible values of a: 1,2,3,4,5,6,7,8,9
possible values of 3*b : 3,6,9,12,15,18,21,24,27

now (a%3) gives 1,2,0,1,2,0,1,2,0
(3*b)%3 gives 0,0,0,0,0,0,0,0,0

now pair those elements of a%3 and 3*b%3 where (a%3 + 3*b%3)%3=0 but dont pair where a=b

finally :
pair 3 with all number except 3 ;number becomes 30000003,31111113,32222223..
pair 6 with all number except 6
pair 9 with all number except 9

so a can have 3 possible values 3,6,9
b can have 8 possible values for each a

ans= 3*8/9*8=1/3

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Hitesh Sharma  (9 years ago)

Number is of the form abbbbbba and is divisible by 3

It is of the form 2a+6b, now
it is should be divisible by 3

now for a=1, b=3 (It is not divisible by 3)
a=2 ,b=6 (It is not divisible by 3)
a=3,b=9 (It is divisible by 3)
and so on....

therefore, for a=(3,6,9),

a+6b form is divisible by 3 and not for any other value of a.

so any number between a_ _ _ _ _ _a is divisible by 3 for a= 3,6 or 9.

So, Finally it comes to,

3C1 * 8C1 / 72

3 because we have to choose from 3 values of a
8 because we have to choose from 8 values of b
72 because a can take 8 values and b can take 9 values overall

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Pappu Kumar Chaudhary  (10 years ago)

koi question comp karo yar

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ankit chauhan  (10 years ago)

option the a) 3/36 b)8/36 c)9/36 @tri do u solution??

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tri  (10 years ago)

yaar kya .. a and b ka ratio pucha tha.. Yaad nai aa raha

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ankit chauhan  (10 years ago)

@kirti did u do that question..i get 9/36 in paper..whats your??

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ankit chauhan  (10 years ago)

@tri yr it is given in the question a>b ??some equality is given

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