Official Quant thread for CAT 2013

@ravi.theja 83
@sagarcat said:
@ravi.theja 83
approach??
@sos2god said:
are u sure we can use euler theorem here...as 78 and 100 share a common factor 2....
right...euler's theorm can't be used here.
@ravi.theja said:
how many perfect squares less than 10^6 are multiples of 24?
@Estallar12 @pirateiim478 do this 😃 post the solution also
@ravi.theja said:
how many perfect squares less than 10^6 are multiples of 24?
Is it 83??
24 = 2^3*3
so the squares will be of the form (12k)^2
hence, total = [1000/12] = 83
@getupsid said:
1) N = 204*221*238*255*......*280. how many consecutive zeroes will be there at the end of this number N?? a. 8b. 10c. 11d. 122) Find the HCF of ((2^100)-1) and ((2^120)-1).a. (2^10)-1b. (2^20)-1c. 1d. none of these
1. Please check the Q again
2. 2^20-1
@ravi.theja said:
1) question is not clear..the first few terms follow a pattern of having difference as 17..but 280 cannot be der.2) 2^HCF(100,120) -1 = 2^20-1
what is the concept involved here man ??@gs4890

how is it the lcm of 100 n 120?? tried binominal too.. but cudnt derive it..
@sos2god Awesome. Got it. Thanks :)
@sos2god
@sos2god said:
5. 166. 387. 168.629. 7810. 22
Can you please explain
Ranjit invests Rs.5000 for 3 years at 5% p.a. compound interest reckoned yearly. Income tax at the rate of 20% on the interest earned is deducted at the end of each year. Find the amount at the end of the third year?
(a) 5624.32 (b) 5630.50 (c) 5788.125 (d) 5627.20
@catahead said:
Ranjit invests Rs.5000 for 3 years at 5% p.a. compound interest reckoned yearly. Income tax at the rate of 20% on the interest earned is deducted at the end of each year. Find the amount at the end of the third year?(a) 5624.32 (b) 5630.50 (c) 5788.125 (d) 5627.20
5624.32?
5000(1.05)-5000=250
250*20/100=50
5000+250-50=5200

5200(1.05)-5200=260..260*20/100=52
5200+260-25=5408

5408(1.05)-5408=270.4....270.4*20/100=54.08
5408+270.4-54.08=5624.32
@catahead
option A
@ravi.theja said:
1) question is not clear..the first few terms follow a pattern of having difference as 17..but 280 cannot be der.2) 2^HCF(100,120) -1 = 2^20-1
@ravi.theja plz explain it.. i dint get it ... though through examples it is correct.. but wats d logic ..
@ravi.theja said:
how many perfect squares less than 10^6 are multiples of 24?
Similar to asking how many numbers less than 1000 are multiples of 12.
So ans is 83.....
@The_Loser said:
A = {1, 2, 3, 4, 5}, B І A and C І B. How many pairs of (B, C) are possible?
5C5*2^5+5C4*2^4+5C3*2^3+5C2*2^2+5C1*2+5C0*1

I am assuming empty set is also a subset
@getupsid said:
1) N = 204*221*238*255*......*280. how many consecutive zeroes will be there at the end of this number N?? a. 8b. 10c. 11d. 122) Find the HCF of ((2^100)-1) and ((2^120)-1).a. (2^10)-1b. (2^20)-1c. 1d. none of these
1. Series is not correct
2. (2^20)-1
@getupsid said:
1) N = 204*221*238*255*......*280. how many consecutive zeroes will be there at the end of this number N?? a. 8b. 10c. 11d. 122) Find the HCF of ((2^100)-1) and ((2^120)-1).a. (2^10)-1b. (2^20)-1c. 1d. none of these
1. Series is not correct
2. (2^20)-1
find the remiander when 7^7^7^7.......7000 times is divided by 17
@ravi.theja said:
find the remiander when 7^7^7^7.......7000 times is divided by 17
E(17) = 16

7^7^.....6999 times/ 16 gives remainder of 7

thus, 7^7 / 17 => 12 should be the remainder.
@gs4890 said:
E(17) = 167^7^.....6999 times / 16 gives remainder of 1thus, 7 mod 17 => 7 should be the remainder.
bhai OA is 12..!! 😃 check karo once again..even am nt getting it