Latest Elitmus Aptitude Question SOLUTION: In a class of 21 students ,we have to organise a quiz competition in which we have to selevt at leat 4 students such that (1 girl and 3 boys) or (1 boy 3 girls.).Boys are 1 more th

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(#M40120758) ELITMUS Numerical Ability question Permutation and combination Keep an EYE

In a class of 21 students ,we have to organise a quiz competition in which we have to selevt at leat 4 students such that (1 girl and 3 boys) or (1 boy 3 girls.).Boys are 1 more than the girls in the class?

Asked In Elitmus MOHAMMAD AMIR (9 years ago)

Unsolved Read Solution (12)

Is this Puzzle helpful?   (23)   (5) Submit Your Solution Permutation and Combination

Read Solution (12) :

Shintala Divya  (9 years ago)

grls(G)=10,boys(B)=11
1 G & 3 B=>10c1*11c3=1650
3 G & 1 G=>10c3*11c1=1320
1650+1320=2970

Is this solution Helpfull? Yes (29) | No   

md saddam hossain  (9 years ago)

g=10,b=11 ans=2970

Is this solution Helpfull? Yes (6) | No   

PHANI CHAND TEKKEM  (9 years ago)

given that boys are 1more than girls.

so B=G+1
=> B-G=1

now we have total no of students 21
i.e B+G=21

solve these two equations

B-G=1
B+G=21

so we get B=11, G=10

no we have to choose 4 students from 21

21c4

for 1 G,3B => 10c1* 11C3= 1650
for 3G,1B => 10C3* 11C1= 1320

1650+1320= 2970

Is this solution Helpfull? Yes (5) | No   

Anuj Rai  (9 years ago)

Solution :
as per the question we have 11 boys and 10 girls
Case-1 when we have to select 1girl and 3 boys
this can be done
11C3*10C1=1320

Case2 when we have to select 1 boy and 3 girls
this can be done
11C1*10C3=1650

Adding both the cases we get
1320+1650= 2970 ways

Is this solution Helpfull? Yes (3) | No   

alok kumar  (8 years ago)

Girl=10, Boys=11 (because Boys are 1 more than the girls in the class)
(10C1 * 11C3) + (10C3 + 11C1)
=1650 + 1320=2970

Is this solution Helpfull? Yes (1) | No   

rishabh jain  (9 years ago)

Can u plz provide the complete solution

Is this solution Helpfull? Yes | No (1)  

kaustubh salunke  (9 years ago)

2970. is the ans.

Is this solution Helpfull? Yes | No   

savita  (9 years ago)

girls =10 ,boys=11
10c1*11c3+11c1*10c3=2970

Is this solution Helpfull? Yes | No   

RAVISH KUMAR  (9 years ago)

10c1*11c3 + 11c1*10c3=2970

Is this solution Helpfull? Yes | No   

Aritra Chakraborty  (9 years ago)

10*11c3+11*10c3=2970

Is this solution Helpfull? Yes | No   

siddharth prakash singh  (9 years ago)

B+(B+1)=21
=>B=11
=>G=10
Req no of ways=(10c1*11c3)+(11c1*10c3)
=1650+1320
=2970 ways

Is this solution Helpfull? Yes | No (1)  

supriya ojha  (8 years ago)

The last two digits will be filled in 8 ways i.e 04,08,12,20,24,32,40,52,20. and the rest will be 3 *3 9 ways thus total 9*8 =72 ways

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