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nam 發問於 科學及數學數學 · 1 十年前

# propability?

Jack and Paul each tosses a coin twice. What is the propability that jack gets the same number of (Tails) as Paul?

sorry !!is probability!!

### 1 個解答

• 1 十年前
最愛解答

For Jack and Paul get the same number of Tails as Paul,

Denote T be tail, H be head.

The possibilities are as followings:

a. Jack: T,T. Paul: T,T

b. Jack: T,T. Paul: T,H

c. Jack: T,T. Paul: H,T

d. Jack: T,T. Paul: H,H

e. Jack: H,T. Paul: T,T

f. Jack: H,T. Paul: T,H

g. Jack: H,T. Paul: H,T

h. Jack: H,T. Paul: H,H

i. Jack: T,H. Paul: T,T

j. Jack: T,H. Paul: T,H

k. Jack: T,H. Paul: H,T

l. Jack: T,H. Paul: H,H

m. Jack: H,H. Paul: T,T

n. Jack: H,H. Paul: T,H

o. Jack: H,H. Paul: H,T

p. Jack: H,H. Paul: H,H

There are totally 16 possibilities. The red fonts represent the events that meet the requirements. There are totally 6 events fulfil the conditions.

So, P(Jack gets the same number of tails as Paul)

= 6 / 16

= 3 / 8

2007-06-02 11:07:31 補充：

For a more convenient method:P(Jack gets the same number of tails as Paul)= P(Jack:T,T and Paul T,T) P(Jack:T,H and Paul:H,T) P(Jack:H,H and Paul H,H)= (1/2 X 1/2) X (1/2 X 1/2) (2 X 1/2 X 1/2) X (2 X 1/2 X 1/2) (1/2 X 1/2) X (1/2 X 1/2)= 1/16 1/4 1/16= 3/8

資料來源： Myself~~~