# Math for Computer science Questions and Answers 271 to 280

## Math for Computer science

### Questions 271 to 280

 271 If the codomain of a function is a subset of real numbers then the function is called (a)  real function                                    (b)  real variable function           (c)  real valued function (d)  real codomain function                     (e)  real range function. 272 If R is a relation represented by the matrix MR = {(0 1 1), (1 1 0), (1 0 1)} then matrix representation of R2  is (a)  {(1 0 1), (1 1 0),(0 1 1)}                     (b)  {(1 0 0), (0 1 0), (0 0 1)}                     (c)  {(0 0 0), ( 1 1 1),( 1 1 1)}                    (d)  {(1 1 1), ( 1 1 1),( 1 1 1)}                    (e)  {(1 0 1), (0 1 1), (1 0 1 )}. 273 Which of the following relation is not an equivalence relation? (a)  x is perpendicular to y                     (b)  x is parallel to y (c)  x - y is an even integer                     (d)  The relation of similarity of triangles     (e)  x = y. 274 An experiment is conducted any number of times under identical conditions whose outcome cannot be predicted with certainty, before the experiment is run is called a (a)  sampling experiment                       (b)  random experiment                          (c)  uncertain experiment                        (d)  vague experiment                 (e)  seldom experiment. 275 A teacher chooses a student at random from a class of 30 girls. What is the probability that the student chosen is a girl? (a)  0                      (b)  1                       (c)  1/2                    (d)  1/30             (e)  cannot say. 276 Series of type fn = fn-1 + fn-2   where f0 = 0 and f1 = 1 is called as    (a)  Fibonacci Series                             (b)  Lemma Series                                  (c)  Lucas Series (d)  Lambda Series  (e)  Laplace series. 277 What is the decrypted message of “ EPP XLI FIWX ” if it is encoded using the encryption key (p–4) mod 26  (a)  YOU ARE BEST                              (b)  ALL ARE GOOD       (c)  ALL THE BEST      (d)  ALL THE WISH                                (e)  ALL THE GOOD. 278 An integer s is an inverse of a modulo m if         (a)  a s (mod m)                                (b)  s a (mod m)                        (c)  s.a 1 (mod m) (d)  m.s 1 (mod a)                                                           (e)  m.a 1 (mod s). 279 The least number of objects required N, so that at least r of them are distributed in one of the k boxes available is (a)  N = k(r-1)                                        (b)  N = k.r                                  (c)  N = k.(r – 1) -1                        (d)  N = k.r + 1                                       (e)  N = k.(r – 1) +1. 280 inverse of 3 modulo 7 is                        (a)  – 2                                                  (b)  5                                                     (c)  4    (d)  both (a) and (b)                                (e)  both (b) and (c).

#### Answers

 271 Answer : (c) Reason : From the definition of the real valued function. 272 Answer : (d) Reason : MR2 = {(0 1 1), (1 1 0), (1 0 1)}× {(0 1 1), (1 1 0), (1 0 1)}= {(1 1 1), ( 1 1 1),( 1 1 1)} 273 Answer : (a) Reason : x is perpendicular to y is not equivalent because a is not perpendicular to x. som this relation si not reflexive. So not equivalent. 274 Answer : (c) Reason : From the definition if uncertain event. 275 Answer : (b) Reason : Because it is a class of 30 girls the student chosen will be certainly a girl. So the probability of choosing a girl is 1. 276 Answer : (a) Reason : From the description of Fibonacci series. 277 Answer : (c) Reason : Because the encryption key is (p–4)mod 26 e is substituted with a, p is substituted with l and likewise so the decrypted message is all the best. 278 Answer : (c) Reason : If s.a 1 (mod m) then s is the inverse of a modulo m 279 Answer : (e) Reason : By the generalized definition of pigeon-hole principle. 280 Answer : (d) Reason : Use Euclidean method to find the inverse of 3 modulo 7. the answer is –2. so the numbers of the form 7p–2 becomes the solution.

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