If 1/a :1/b :1/c=3:4:5,\nthen a : b : c\n (a)\n5:4:3\n(b) 20 : 15 : 12\n (c)\n9: 12 : 15\n(d) 12...

If (1)/(a):(1)/(b):(1)/(c)=3:4:5, then a:b:c5:4:3(b)20:15:12^(c):12:15(d)12:15:20

If C(20,3):C(n,2)=12:1, then n=

If the n^(th) term of an A.P.is (2n+1), then the sum of its first three terms is (a) 6n+3 (b) 15 (c) 12 (d) 21

A ,\ B\ a n d\ C can reap a field in 15 3/4 days : B ,\ C\ a n d\ D in 14 days: C ,\ D\ a n d\ A in 18 days: D ,\ A\ a n d\ B in 21 days. In what time can A ,\ B ,\ C\ a n d\ D together reap it?

If A : B=2:3, B : C=2:4 a n d C : D=2:5, t h e n A : D is equal to 1:5 b. 2:15 c. 4:5 d. 5:2

If (12^(n)+1)backslash is divisible by 13, then n is (a) 1 only (b)12 only (c) any odd integer (d) any even integer

If the mean of first n natural numbers is (5n)/9 , then n= (a) 5 (b) 4 (c) 9 (d) 10

The value of |1 1 1\ ^n C_1\ ^(n+2)C_1\ ^(n+4)C_1\ ^n C_2\ ^(n+2)C_2\ ^(n+4)C_2| is (a) 2 (b) 4 (c) 8 (d) n^2

If ^(n+1)C_3=2.^nC_2, then n= (A) 3 (B) 4 (C) 5 (D) 6