Business Mathematics

281. The probability of a bomb hitting a bridge is ½ and two direct hits are needed to destroy it. The least number of bombs required so that the probability of the bridge being destroyed is greater than 0.9 is

  1. 8
  2. 9
  3. 10
  4. 11
Correct answer: (B)
9

282. Find the number of non-congruent rectangles that can be found on a normal 8*8 chessboard

  1. 24
  2. 36
  3. 48
  4. None of these
Correct answer: (B)
36

283. Solve -x +2y -3z = 2
-2y = 3
2x -y +z = 9

  1. x =5/2, y =7/2, z=-7/2
  2. x=-3/2, y=-11/2, z=-7/2
  3. x=11/2, y=-3/2, z=-7/2
  4. x=-7/2, y= -3/2, z=-11/2
Correct answer: (C)
x=11/2, y=-3/2, z=-7/2

284. Is (x+y)(x-y) = -7

  1. Linear
  2. Non linear
  3. Monomial
  4. None
Correct answer: (B)
Non linear

285. The number of non zero rows of a matrix in its row echelon form is a

  1. Row matrix
  2. Column matrix
  3. Rank of matrix
  4. Augmented matrix
Correct answer: (C)
Rank of matrix

286. A square matrix with each of its diagonal elements equal to unity and all non diagonal elements equal to zero is

  1. Scalar matrix
  2. Null matrix
  3. Identity matrix
  4. Column matrix
Correct answer: (C)
Identity matrix

287. Find the transpose of A= 1 -1
2 3

  1. 2 3
    1 -1
  2. 1 2
    -1 3
  3. 3 2
    1 -1
  4. 3 1
    2 -1
Correct answer: (B)
1 2
-1 3

288. Which of the following is correct:

  1. Determinant is a square matrix
  2. Determinant is a number associated to a square matrix.
  3. Determinant is a number associated to a matrix.
  4. None of these.
Correct answer: (B)
Determinant is a number associated to a square matrix.

289. Find values of k if area of triangle is 3sq. units and vertices are (1,3), (0,0) and (k,0)

  1. +3
  2. -3
  3. ± 1
  4. ±2
Correct answer: (D)
±2

290. Let A be a non singular matrix of order 3 x3.Then |adj A | is equal to

  1. |A |
  2. |A |2
  3. | A |3
  4. 3 | A|
Correct answer: (B)

|A |2

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