Official Quant thread for CAT 2013

MBA CAT 2024
21626
@Estallar12 said:
Favourable Events = 8*7 + 7*8 = 112.Sample Space = 64C2.Probability = 112/64C2 = 1/18.
can u plzz xplain fav cases wala part....
nahi samajh me aaya... plzz
21627
@Dexian said:
can u plzz xplain fav cases wala part....nahi samajh me aaya... plzz
In each row we will have 7 ordered pairs which share common side
so in 8 rows=7*8
in 8 columns=7*8
so total=112
21628

For how many values of N is

N^4-20N^2+4 is prime?

21629

how many different sums can be formed with the following coins

5rs ,1 rs ,50ps, 25ps, 10ps, 3ps ,2ps ,1ps

21630
@raopradeep said:
how many different sums can be formed with the following coins5rs ,1 rs ,50ps, 25ps, 10ps, 3ps ,2ps ,1ps
Umm....254?

regards
scrabbler
21631
@scrabbler
bhai explain kar yaar

21632
@2013IsMine said:
For how many values of N isN^4-20N^2+4 is prime?
@scrabbler kindly help sir!.:)
21633
@raopradeep said:
how many different sums can be formed with the following coins5rs ,1 rs ,50ps, 25ps, 10ps, 3ps ,2ps ,1ps
255 ??
21634

five balls of different colours are to be placed in three different boxes such that any box contains atleast one ball . find maximum number of different ways to do this

90
120
150
180

21635
@Dexian
bro explain plz i think 1 case issme minus hona chaiye
21636
@raopradeep said:
@scrabblerbhai explain kar yaar
No formal approach....just said that all possible combinations can be written as 2^8 - 1 = 255 (2^8 since each coin can be either selected or not selected, and -1 for the case of no coin selected) and then I tried to eliminate whatever overlaps were there (wherever multiple such combos give the same total) and the only case I found was 1+2 = 3 (all the other coin values are greater than the sum of all smaller coins! so no overlap possible) So 1 case was double counted and I minused it to get 254. Dunno if there is a "formal" way to solve...

regards
scrabbler
21637
@raopradeep said:
five balls of different colours are to be placed in three different boxes such that any box contains atleast one ball . find maximum number of different ways to do this90120150180
150? but i think 500 is also a possibility
21638
@scrabbler me too tried the same way
21639
@iLoveTorres i got 150 oa is also 150
but how 500 explain ?

21640

@iLoveTorres said:
150? but i think 500 is also a possibility
30+180=210??
21641
@Dexian
@Dexian said:
30+180=210??
explain kar bhai kaise ?

21642
@iLoveTorres said:
150? but i think 500 is also a possibility
How 500? Even with no conditions, 5 balls in 3 boxes is max 3^5 = 243 ways...usse to kam hi hoga!

regards
scrabbler
21643
@Dexian said:
30+180=210??
bro consider the case of (1,2,2)
so it is (5c1*3[3 ways of selecting a box])*(4c2*2[2 ways of selecting a box])*2c2*1=180.

@scrabbler bhai wats the mistake i am doing?
21644
@scrabbler said:
How 500? Even with no conditions, 5 balls in 3 boxes is max 3^5 = 243 ways...usse to kam hi hoga!regardsscrabbler
meine galti se 5c1*5c2*5c2 soch liya.. kal aap ne hi toh bola tha ki think before you try it out on paper 😛 so choti galti ho gayi
21645

(3 1 1)+(2 2 1)=
5c3 * 3! + 5c4 * 4c2 *3!