SOLUTION: A ball is drawn at random from a box containing 10 red balls, 30 white balls, 20 blue balls and 15 black balls. Obtain the probability that the ball drawn is a) black or red b)

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Question 1157521: A ball is drawn at random from a box containing 10 red balls, 30
white balls, 20 blue balls and 15 black balls. Obtain the probability
that the ball drawn is
a) black or red
b) not red or blue
c) not blue
d) white
e) red, white or blue
Answer by Edwin McCravy(20064) About Me  (Show Source):
You can put this solution on YOUR website!
A ball is drawn at random from a box containing 10 red balls, 30
white balls, 20 blue balls and 15 black balls. 
There are 10 reds +30 whites + 20 blues + 15 blacks = 75 balls in the box.
a) Obtain the probability
that the ball drawn is black or red
15 blacks + 10 reds
------------------- = 25/75 = 1/3
     75 balls
b) Obtain the probability
that the ball drawn is not red or blue
30 whites + 15 blacks 
--------------------- = 45/75 = 3/5
      75 balls
c) Obtain the probability
that the ball drawn is not blue
10 reds + 30 whites + 15 blacks
------------------------------- = 55/75 = 11/15
          75 balls
d) Obtain the probability
that the ball drawn is white
  30 whites 
------------------- = 2/5 
  75 balls
e) Obtain the probability
that the ball drawn is red, white or blue
 
10 reds + 30 whites + 20 blues
------------------------------- = 60/75 = 4/5
          75 balls

Edwin