Question 11.2.25
The outer circle has a diameter of 8 feet, which cuts in half to a 4 foot radius.
The area of the outer circle is A = pi*r^2 = pi*4^2 = 16pi
The inner circle has a radius of 2 feet (which is half of the diameter 4 ft), so that would lead to an area of 4pi
The difference in areas is 16pi-4pi = 12pi
The value 12pi is the area of the red ring. Divide this over 16pi to get the probability of landing in the red area
(12pi)/(16pi) = 12/16 = 3/4 = 0.75
Answer: 0.75
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Question 11.2.9
Add up everything in the bottom row to get 274
Then divide each value over 274 to get the corresponding probability.
For example, 47/274 = 0.172 represents the approximate probability of rolling a 1 and 45/274 = 0.164 is the approximate probability of rolling a 2 and so on.
You should have these six answers:
- The experimental probability of rolling a 1 is 0.172
- The experimental probability of rolling a 2 is 0.164
- The experimental probability of rolling a 3 is 0.157
- The experimental probability of rolling a 4 is 0.164
- The experimental probability of rolling a 5 is 0.175
- The experimental probability of rolling a 6 is 0.168
Those six values are approximate.
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Question 11.3.13
Since A and B are independent, we can say,
P(A and B) = P(A)*P(B)
P(A and B) = (1/6)*(3/5)
P(A and B) = (1*3)/(6*5)
P(A and B) = 3/30
P(A and B) = 1/10
P(A and B) = 0.1
Answer: 0.1