`A B C D` is a square `A-=(1,2),B-=(3,-4)dot` If line `C D` passes through `(3,8),` then the midpoint of `C D` is (a) `(2, 6)` (b) `(6,2)` (c) `(2,5)` (d) `((28)/5,1/5)`

5 tan^2 A -5sec^2 A+1 is equal to (a) 6 (b) -5 (c) 1 (d) -4

If [(2a+b,a-2b),(5c-d,4c+3d)]=[(4,-3),(11,24)] then the value of a+b-c+2d is (a) 8 (b) 10 (c) 4 (d) -8

The mean of 5 observations is 5 and their variance is 124. If three of the observationsare 1,2 and 6, then the mean deviation from the mean of the data is (1)2.4 (b) 2.8 (c) 2.5 (d) 2.6

Find C( 6 , 3 ) - C( 5 , 3 ) is equal to : a ) C( 6 ,2 ) b ) C ( 5, 3 ) c ) C( 1, 0 ) d ) C( 5, 2 )

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

Which one of the following is wrong? (9)/(4)+1.75=4( b) (9)/(5)+2.2=4(c)(6)/(5)+2.8=4(d)(3)/(2)+1.5=4

Prove that the points A(0, 4, 1), B(2, 3, -1), C(4, 5, 0) and D(2, 6, 2) are vertices of a square.

If A : B = 5 : 2, B : C = 2 : 3 and C: D = 5: 3 , then the ratio A: B : C : D is