Discrete Mathematics Answers

Perform the following modular arithmetic by applying the addition/subtraction rule.

(a) (9+15) mod 7

(b) (15-23) mod 5

(c) (-47 x (5+1)) mod 5

Find the value of x if 2x ≡ 7 (mod 11). (*Hint: The value of x should be between 0 to 10)

Find five different integers a such that a≡3 (mod 6)

I do my laundry every 20 days. Last week, laundry day fell on a Friday. On what day of the week will laundry fall next?

Which of the following expressions are equivalent to: (-171 x 77) mod 16 Select all that applies

a) 1

b) (5 x 13) mod 16

c) 2

d) 65 mod 16

e) 18 mod 16

What is 6 mod 9 + 11 mod 9 congruent to?

a) 8 mod 9

b) 6 mod 9

c) 7 mod 9

d) 0 mod 9

What is 7 mod 3?

a) 1 mod 3

b) 2 mod 3

c) 3 mod 3

d) 0 mod 3 

Draw a graph having the given properties

(a) Four vertices each of degree 1

(b) Six vertices each of degree 3 

When drawing one card out of a deck of 52 playing cards, what is the probability of getting heart or a face card? There are 13 hearts and a total of 12 face cards (3 of each suit: spades, hearts, diamonds and clubs), but only 3 face cards of hearts.

45% of the children in a school have a dog, 30% have a cat, and 18% have a dog and a cat. What percentage of those who have a cat also have a dog?