Probability of a Red or Odd numbered marble

Question

A jar contains 10 red marbles numbered 1 to 10 and 10 blue marbles numbered 1 to 10. A marble is drawn at random from the jar. Find the probability of the given event, please show your answers as reduced fractions.

(a) The marble is red. P(red)=   

(b) The marble is odd-numbered. P(odd)=   

(c) The marble is red or odd-numbered. P(red or odd) =   

(d) The marble is blue or even-numbered. P(blue or even) =   

Answer 1

20 total marbles

a) P(red) = 10/20 = 1/2

b) P(odd-numbered): 10/20 = 1/2

c) P(red or odd-numbered) = P(red) + P(odd numbered) - P(red and odd-numbered) = 10/20 + 10/20 - 5/20 = 15/20 = 3/4

d) P(blue or even-numbered) = P(blue) + P(even numbered) = P(blue and even numbered) = 10/20 + 10/20 - 5/20 = 15/20 = 3/4