# Math for Computer science Questions and Answers 181 to 190

## Math for Computer science

### Questions  181 to 190

181.
If a procedure is broken into a sequence of two tasks. If there are n1 ways to do the first task
and n2 ways to do the second task, then there are _____ ways to do the procedure.
 (a) n1-n2 (b) n1+n2 (c) n1x n2 (d) n1/n2 (e) n1 | n2.
182.
If first task can be done in n1 ways, second task can be done in n2 ways, and if
both cannot be done at the same time, then, the total number of ways to do the task is
 (a) n1-n2 (b) n1+n2 (c) n1*n2 (d) n1/n2 (e) n1 | n2.
183.
The Cryptosystem based on Modular Exponentiation Modulo and  the product of two
large prime numbers is called as
 (a) RSA Encryption (b) DES Encryption (c) CRC Encryption (d) PGP Encryption (e) Affine Transformation.
184.
The total number of r-combinations from a set with n-elements when repetition of
elements is allowed is
 (a) C(n + r –1) (b) C(n – r –1) (c) C(n + r + 1) (d) C(n – r + 1) (e) C( (n / r) + 1).
185.
In Hashing, when more than one file is assigned to single memory location, then it is called as
 (a) Collection (b) Crashing (c) Chaining (d) Collision (e) Coherence.
186.
The product of two numbers is
27.3852.7.11 and their gcd is 23.34.5. What is their LCM?
 (a) 24.33.5.711 (b) 24.3.5.7 (c) 24.34.5.711 (d) 2.34.5.711 (e) 2.3.5.7.
187.
What is the probability that a randomly selected day of a leap year is in February?
 (a) 28/365 (b) 28/366 (c) 29/365 (d) 29/366 (e) 30/366.
188.
What is the probability that a card chosen randomly from a deck is an ace or a heart?
 (a) 13/52 (b) 1/13 (c) 16/52 (d) 17/52 (e) 4/13.
189.
Which of the following condition is true with respect to the probability of a sample
space p(S) Where S is the sample space?
 (a) p(S)  > 1 (b) 0 < p(S) >1 (c) 1> p(S) ≥ 2 (d) p(S) = 0 (e) p(S) = 1.
190.
What is the probability that a number selected within the range of 1…100, is divisible by 5?
 (a) 1 / 20 (b) 1 / 5 (c) 1 / 25 (d) 1 / 4 (e) 1/ 100.

#### Answers

 181 Answer : (c) Reason:  by product rule 182 Answer : (b) Reason:  by the sum rule 183 Answer : (a) Reason:  by the method of  RSA Encryption 184 Answer : (a) Reason:  by the definition of combinations  with repetitions are allowed. 185 Answer : (d) Reason:  by the definition of collision 186 Answer : (c) Reason:  by the definition of  LCM 187 Answer : (d) Reason:  in a leap year there are  366 days and February will  have 29 days so the probability is 29/366 188 Answer : (c) Reason:  in the pack of cards there are 4 aces , 13 hearts and one card heart ace in common so by addition theorem of probability 4/52+13/52-1/52=16/52 189 Answer : (e) Reason:  by the axiomatic definition of probability 190 Answer : (b) Reason:  there are 20  numbers which are divisible by 5 so the probability is 20/100 = 1/5

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