Need Steps Thx!
1) There are 7 cards and they are numbered from 1 to 7. A card is selected at random. If the number shown on the card selected is odd, 2 points are given; if it is even, 2 points is deducted. Find the expected score.
2) Terry chooses at random a number from 2, 4 and 6, while Jack chooses at random a letter from the vowels. Find the probability that the result is ‘4’ and ‘E’.
F3 Maths -- Need Steps (4)
2007-08-13 12:41 am
回答 (4)
2007-08-13 12:50 am
✔ 最佳答案
1) Expected score:4/7 x 2 + 3/7 x (-2)
= 2/7
P.S. : 4/7 : P(Odd), 3/7 : P(Even)
2) P ( 4 & E) :
1/3 x 1/5
= 1/15
P.S. vowels: A,E,I,O,U
2007-08-13 12:59 am
1)point: 2 -2
probaility: 4/7 3/7
the expected score : 2(4/7) + (-2)(3/7)
=2/7
2) probability of getting 4: 1/3
probability of getting E: 1/5
the probability that the result is‘4’ and 'E’: 1/3 X 1/5 = 1/15.
probaility: 4/7 3/7
the expected score : 2(4/7) + (-2)(3/7)
=2/7
2) probability of getting 4: 1/3
probability of getting E: 1/5
the probability that the result is‘4’ and 'E’: 1/3 X 1/5 = 1/15.
2007-08-13 12:48 am
4/7*2 + 3/7*(-2)
= 8/7-6/7
= 2/7
= 8/7-6/7
= 2/7
收錄日期: 2021-04-25 15:39:11
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