Latest Elitmus Aptitude Question SOLUTION: Raj wants to buy 7 floors in an 68 storied building whose numbering stars from 1 upto 68.but it has to follow certain rules which are as follows 1)none of the floor should be a pr

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(#M40157603) ELITMUS Numerical Ability question logical 2nd oct 2016 Keep an EYE

Raj wants to buy 7 floors in an 68 storied building whose numbering stars from 1 upto 68.but it has to follow certain rules which are as follows

1)none of the floor should be a prime number

2)none of the digit of the floor should be a prime number

3)Raj cannot buy the 1st floor as it is being assigned to the architect.

SO how many options are left with Raj to buy the floor

option)
1). 11
2). 13
3). 15
4). 17

Asked In Elitmus SHUBHAM (7 years ago)

Solved Mallikarjuna Reddy Read Solution (17)

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Read Solution (17) :

Mallikarjuna Reddy  (7 years ago) Best Solution

eliminate the numbers from 1 to 68 based on given conditions
1)should not be a prime number
-->There are 19 prime numbers from 1 to 68. So, we are left with 68-19=49 floors
2)digit of the floor should not be a prime number
-->There are 31 numbers like that (excluding prime numbers). So, we have 49-31=18 floors to choose
Again, in this 18 floors we have to take out 1st floor because we are not allowed to select
Finally, we have 18-1=17 options left

Is this solution Helpfull? Yes (33) | No (1)  

yudhveer kumar singh  (7 years ago)

Since floor starts form the 1 therefore 2 will be the 1st floor.
Form 1 to 10 only 4,6,8,9,10 are not prime.
Form 11 to 20 only 14 ,16,18 are not prime also non of their digits are prime.
From 21 to 30 each number has a prime number so it must no be consider.
In between 40 to 49 we have to consider only 40,44,46,48,49.
50 to 59 follow either of the condition so we have too neglect it.
In between 60 to 68 60,64,66,68.
total option =17.

Is this solution Helpfull? Yes (26) | No (3)  

Anurag patel  (7 years ago)

Ans is 17
4,6,8,9,10,14,16,18,40,44,46,48,49,60,64,68,66

Is this solution Helpfull? Yes (6) | No (1)  

prafful namburi  (7 years ago)

13 as there will be 6 non primes between 0-9 6c2=15 ,raj cant stay in 1st floor and 0th floor so 15-2=13

Is this solution Helpfull? Yes (3) | No (11)  

OMi  (7 years ago)

15
4,6,8,9,10,14,16,18,44,46,48,49,64,66,68

Is this solution Helpfull? Yes (1) | No (10)  

PRIYANKA  (7 years ago)

the ans is 17

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

Venkat Ramana  (7 years ago)

2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67 these are total prime numbers btw 1 to 68 so there are 11 ways how raj can buy 7 floors

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

sudhansu  (6 years ago)

17
This problem is permutation problem
0,1,2, 3,4,5,6,7,8,9 =D digits
No digit can be prime D-{2,3,5,7}
Now how many ways we can make max
two digit number less than 70 excluding 0 and 69
_ _=4(including 0,1,4,6 digits)×6(including 0,1,4,6,8,9)=24-2(00,69)=22
Now no no can be prime and can't be 1 floor
=22-(prime no b/w 1 to 68)4-1=17

Is this solution Helpfull? Yes (1) | No   

abhishek  (7 years ago)

4.) the required numbers can be 4,6,8,9,10,14,16,18,40,41,44,46,48,49,60,64,66,68.So total number=17.

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Devraj  (7 years ago)

from 1 to 68 number that not to be consider are 1(according condition 3),2,3,5,7,11,13,17,19,23,29,31,37,43,47,53,59,61,67.
68 - 19 = 49.
now imposing second condition by removing all number from digit 1,2,3,5,7 even if they are not prime(condition2).
4,6,8,10,14,16,18,40,44,46,48,49,64,66,68
so total is 15.

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Hemant Kanyal  (7 years ago)

17 is the answer.

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Himanshu kumar  (7 years ago)

17 options left by eliminating all the conditions

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bhavya gupta  (7 years ago)

option 4 17 is correct

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Sunny Kumar  (7 years ago)

eliminate the numbers from 1 to 68 based on given conditions
A) ........ Should not be a prime number ?
There are 19 prime numbers from 1 to 68. So, we are left with 68-19=49 floors
B) ....... Digit of the floor should not be a prime number ?
There are 31 numbers like that (excluding prime numbers).
So, we have 49-31=18 floors to choose
Again, in this 18 floors we have to take out 1st floor because we are not allowed to select
Finally, we have 18-1=17 options left

Is this solution Helpfull? Yes | No   

RAVI NANDAN LOHAR  (7 years ago)

eliminate the numbers from 1 to 68 based on given conditions
1)should not be a prime number
-->There are 19 prime numbers from 1 to 68. So, we are left with 68-19=49 floors
2)digit of the floor should not be a prime number
-->There are 31 numbers like that (excluding prime numbers). So, we have 49-31=18 floors to choose
Again, in this 18 floors we have to take out 1st floor because we are not allowed to select
Finally, we have 18-1=17 options left

Is this solution Helpfull? Yes | No (1)  

Shubham  (6 years ago)

Form 1 to 10 only 4,6,8,9,10 are not prime.
Form 11 to 20 only 14 ,16,18 are not prime also none of its digits are prime.
From 21 to 30 each number has a prime number so must no need to consider.
In between 40 to 49 we consider only 40,44,46,48,49.
50 to 59 has none.
In between 60 to 68 their are 4 numbers: 60,64,66,68.
total option =17.

Is this solution Helpfull? Yes | No   

Satyam dixit  (3 years ago)

Ans 13).

acc. to rules 1)none of the floor should be a prime number

2)none of the digit of the floor should be a prime number

3)Raj cannot buy the 1st floor as it is being assigned to the architect.


set of options will be (4,6,8,9,40,44,46,48,49,60,64,66,68) 13 options

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