Latest Elitmus Aptitude Question SOLUTION: is X=(100-n /n) a prime no? i) n>4 II) n^2=25

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(#M40154996) ELITMUS Numerical Ability question Data sufficiency Keep an EYE

is X=(100-n /n) a prime no?

i) n>4

II) n^2=25

Asked In Elitmus Bushra (8 years ago)

Unsolved Read Solution (7)

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NAVEEN KUMAR  (8 years ago)

first go thrgh S->1 i.e n>4 if check for n=10 then X=(100-10)/10=9(not prime)
So,S->1 is insufficient
then Go for S->2
i.e n^2=20..>n=-5,5
put n=-5, X=(100-(-5))/-5=-21(not prime)
So,S->1 is also insufficient
if we consider both S-> 1 & 2 (i.e n>4 & n^2=25 then the value of n=5 by both Statement)
So, if n=5 then X=(100-5)/5=19(prime no)
hence, Statements I and II together are necessary to answer the question

Is this solution Helpfull? Yes (39) | No (2)  

rituraj  (8 years ago)

Both statement are required to answer the question.
1. is insufficient because if we put n=5 ,then X=19 which is a prime but if we put n=10,X=9 which is a composite number.
2. alone is not sufficient as n can be either +5 or -5,,,,+5 gives us 19 which is prime and -5 gives us 21 which is composite.
1+2 : n=5 we can say because n>4+n=5^2,,,,,,therefore -5 is invalid and only +5 is left which is a prime.

Therefore Answer= 1+2 :)))))

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

NAVEEN KUMAR  (8 years ago)

@ Neha hoe Opt 2 is alone possible
S-2....>n^2=25( here value of n=5,-5)
if u put n=-5 then u got X=-21((100-(-5))/-5)
so,-21 is not a prime no

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

Bushra  (8 years ago)

i think option 2 is directly giving us a prime no.. so no need of option a..
then answer should be a) this can be solve throungh one of the answer alone but cannot be answered by using other statements alone..

Is this solution Helpfull? Yes (1) | No (5)  

Piyush jain  (8 years ago)

both statements are necessary

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

Himanshu Kumar  (7 years ago)

I and II both together necessary to answer the question
n^2=25
n=+5,-5
n=-5 does not give prime no.
so that we will go through n=5 it will give us prime no.
which satisfy both condition(i.e n>4)

Is this solution Helpfull? Yes (1) | No   

Vipin  (4 years ago)

II is sufficient only

Is this solution Helpfull? Yes | No   

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