SOLUTION: b) The Weather Office forecasts the probability of a rainfall the next day as forty-two percent. What is the probability that it will not rain?

Algebra ->  Probability-and-statistics -> SOLUTION: b) The Weather Office forecasts the probability of a rainfall the next day as forty-two percent. What is the probability that it will not rain?       Log On


   



Question 1114092: b) The Weather Office forecasts the probability of a rainfall the next day as forty-two percent. What is the probability that it will not rain?


c) Which of the followings are not probabilities?
a) 0.005
b) 1.02
c) ¼
d) 101%

d) A box contains 5 blue, 7 red and 8 yellow balls. A ball is drawn at random. What is the probability that the ball drawn is not yellow? (2 marks)
e) How many blue balls have to be added to the box to increase the probability of picking a blue ball at random to 50%?

Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
b) It must either rain or not rain so,
P%5BNR%5D%2B0.42=1
P%5BNR%5D=1-0.42
.
.
.
c) Probability must a number between 0 and 1.
.
.
.
d) Find the probability that the ball is yellow.
P%28Y%29=8%2F%285%2B7%2B8%29=8%2F20=2%2F5
So the complement would be the probability of not yellow.
P%28NY%29=1-2%2F5
P%28NY%29=3%2F5
.
.
e) P%28B%29=1%2F2
Let the number of blue balls added be equal to X,
%285%2BX%29%2F%2820%2BX%29=1%2F2
2%285%2BX%29=1%2820%2BX%29
10%2B2X=20%2BX
X=20-10