Latest Elitmus Aptitude Question SOLUTION: Find the probability of (x^4)+4 divisible by 5 ? a) 8/9 b) 2/5 c) 3/5 d) 1/5

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(#M40040666) ELITMUS Numerical Ability question Probability Keep an EYE

Find the probability of (x^4)+4 divisible by 5 ?
a) 8/9
b) 2/5
c) 3/5
d) 1/5

Asked In Elitmus Dipanshu Singhal (9 years ago)

Unsolved Read Solution (10)

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Read Solution (10) :

Alakh Niranjan Singh  (9 years ago)

for the divisibility of y by 5 the last digit should be either 0 or 5
the equation y=x^4+4 it will divisible by 5 if last digit will be 0 or 5
so it will happen when the x^4 either 1 or 6
for 1 it should be 1^4,3^4,7^4,9^4
and for 6 it should be 6^4,4^4,8^4,2^4
so sample set should be {0,1,2,3,4,5,6,7,8,9,}
and event set is {1,2,3,4,6,7,8,9}
so probability is
8/10=4/5 ans

Is this solution Helpfull? Yes (43) | No (5)  

Vikram  (9 years ago)

answer is 8/9 because in x =1,2,3,4,6,7,8,9 satisfy that equation only 5 not satisfy that equation so answer is 8/9

Is this solution Helpfull? Yes (12) | No (3)  

Aparna Bajpai  (9 years ago)

ans= 4/5

for div by 5 unit digit shud b 5 or 0

for 0, x can b 2, 4,,6,8,12,14,16,18......like that total 40 values for x

for unit digit 5 x can be 1, 3, 7,9,11,13,17,19....like 40 values

so in 100 total possible values for x are 80

prob=80/100=4/5

Is this solution Helpfull? Yes (6) | No (4)  

oshank karn  (9 years ago)

guys there was one more condition in this question that x is a 4digit no
for the divisibility of y by 5 the last digit should be either 0 or 5
and the equation says (x^4)+4 =5
it means the last digit can not be zero boz 0+4 will lead to last digit 4 which is not divisible by 5
so the last digit of x^4 should be 1
and only 1^4 3^4 7^4and 9^4 satisfies the condition
so the sample set s=0,1,2,3,4,5,6,7,8,9.
n(s)=10
and event set =1,3,7,9
n(e)=4
so the probability will be n(e)/n(s)=4/10=2/5
so 2/5 is answer

Is this solution Helpfull? Yes (4) | No (15)  

akash verma  (9 years ago)

soorrrry !!!!!!!!!!
ans 8/9 hoga damn sure !!!

Is this solution Helpfull? Yes (3) | No (4)  

akash verma  (9 years ago)

ans 4/5 hogaa yaar option sure ho ki sahii h??

Is this solution Helpfull? Yes (1) | No   

vineysagar  (9 years ago)

i think 8/9 is right one..... becoz 0 to 9 only x=5 is there which is nt divided by 5.....

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sumit gupta  (9 years ago)

Oshank Karn here one more condition apply
for the divisibility of 5 unitary digit should be 0 or 5
and our eq is x^4 +4 =5
it means the last digit should be 1 or 6
for 1 it should be 1^4,3^4,7^4,9^4
and for 6 it should be 6^4,4^4,8^4,2^4
so sample set should be {1,2,3,4,5,6,7,8,9,}
and event set is {1,2,3,4,6,7,8,9}
so probability is 8/9

Is this solution Helpfull? Yes (1) | No (3)  

sridhar  (9 years ago)

chances of last digit being 0 , 5 will fail only in case of any number^4+4 except last digit containing 0,5 is divisible by 5 8/9 is the best answer

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Aman Pamecha  (9 years ago)

C 3/5
x=0-9
and find the unit digit for every value of x and add 4 , then chk it is divisible by 5 or not
so we have find 6 value 0,1,3,6,7,8 which r divisible by and total is 10(0-9) so
6/10=3/5

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