A number is chosen at random from the integers 10 to 30 inclusive .find the probability that the number is a) a multiple of 3 b) a multiple of 5 c) prime d) a perfect square.

Answer 1

There are 21 integers from 10 to 30 inclusive, (count on your fingers if you think there are only 20)
multiples of 3 are 12, 15, 18, 21, 24, 27, and 30
prob(a multiple of 3) = 7/21 = 1/3

make a similar analysis for the primes from 10 to 30,
as well as the perfect squares from 10 to 30

Answer 2

Write an equation that is true when x is equal to −5, 4, 0 and for no other values of x.

Answer 3

30/21