121.

The arithmeic mean of the scores of a group of students ia a test was 52. The brightest 20% of them secured a mean score of 80 and the dullest 25%, a mean score of 31. The mean score of remaining 55% is

• 54.6%

• 45%

• 50%

• 51.4%

If cosx + cos²x = 1, then the numerical value of (sin¹²x + 3 sin¹⁰x + 3 sin⁸x + sin⁶x - 1) is

• 0

• 1

• -1

• 2

ABCD is a rhombus. AB is produced to F and B produced to E such that AB = AE = BF. Then,

• ED² + CF² = EF²

• ED || CF

• ED > CF

• 

If x ≠ 0,  y ≠ 0  and z ≠ 0 and 
,  then the relation among x, y and z is

• 

• x = y = z

• x + y + z = 0

• x + y = z

Two pipes P and Q can fill a cistern in 12 and 15 min, respectively. If both are opened together and at the end of 3 min, the first is closed. How much longer will the cistern take to fill?

• 

• 

• 5 min

• 

If x² + y² + z² = 2(x - y - z) - 3, then the value of 2x - 3y + 4z is (assume that x, y and z) are all real numbers).

• 3

• 0

• 9

• 1

The square root of  is

In a ΔABC, ∠A : ∠B : ∠C = 2 : 3 : 4, A line CD is drawn || to AB, then ∠ACD is

• 80°

• 20°

• 40°

• 60°

If  then the value of 12 * 4 is

• 48

• 19

• 20

• 21

A, B and C walk 1 km in 5 min, 8 min and 10 min, respectively. C starts walking from a point, at a certain time, B starts from the same point 1 min later and A starts from the same point 2 min later than C. Then, A meet B and C at times

• 2 min, 3 min

• 

• 2 min,  

• 1 min, 2 min