2006-06-09 04:09:04 · 8 answers · asked by Kevin 2 in Science & Mathematics ➔ Mathematics
Probability of 10 heads, 1/2^10 = 1/1024
Probability of 9 heads 10/2^10 = 10/1024
Probability of 8 heads 45/2^10 = 45/1024
Probablity of at least 8 heads =
Probablity of 10 heads + Probability of 9 heads + Probability of 8 heads = 56/1024 = 7/128.
2006-06-09 04:20:44 · answer #1 · answered by rt11guru 6 · 2⤊ 0⤋
First you need to find out how many ways there are to get at least 8 heads
1 HHHHHHHHHH
2 THHHHHHHHH
3 HTHHHHHHHH
4 HHTHHHHHHH
5 HHHTHHHHHH
6 HHHHTHHHHH
7 HHHHHTHHHH
8 HHHHHHTHHH
9 HHHHHHHTHH
10 HHHHHHHHTH
11 HHHHHHHHHT
12 TTHHHHHHHH
13 THTHHHHHHH
14 THHTHHHHHH
15 THHHTHHHHH
16 THHHHTHHHH
17 THHHHHTHHH
18 THHHHHHTHH
19 THHHHHHHTH
20 THHHHHHHHT
21 HTTHHHHHHH
22 HTHTHHHHHH
23 HTHHTHHHHH
24 HTHHHTHHHH
25 HTHHHHTHHH
26 HTHHHHHTHH
27 HTHHHHHHTH
28 HTHHHHHHHT
29 HHTTHHHHHH
30 HHTHTHHHHH
31 HHTHHTHHHH
32 HHTHHHTHHH
33 HHTHHHHTHH
34 HHTHHHHHTH
35 HHTHHHHHHT
36 HHHTTHHHHH
37 HHHTHTHHHH
38 HHHTHHTHHH
39 HHHTHHHTHH
40 HHHTHHHHTH
41 HHHTHHHHHT
42 HHHHTTHHHH
43 HHHHTHTHHH
44 HHHHTHHTHH
45 HHHHTHHHTH
46 HHHHTHHHHT
47 HHHHHTTHHH
48 HHHHHTHTHH
49 HHHHHTHHTH
50 HHHHHTHHHT
51 HHHHHHTTHH
52 HHHHHHTHTH
53 HHHHHHTHHT
54 HHHHHHHTTH
55 HHHHHHHTHT
56 HHHHHHHHTT
So there are 56 ways to gave at least 8 heads.
The total number of ways to throw the ten coins is 2^10
So the probability is 56/2^10
Or 7/2^7=7/128
2006-06-09 04:31:02 · answer #2 · answered by fredorgeorgeweasley 4 · 0⤊ 0⤋
Probability of getting atleast 8 heads is the sum of the probability of getting 8, 9 and 10 heads.
The mathmatical formula using combinations is:
10C8*(1/2)^8+10C9*(1/2)^9+(1/2)^10 = 56/1024
as stated by a poster above.
2006-06-09 04:40:24 · answer #3 · answered by Ink 1 · 0⤊ 0⤋
the sum is 10*8
2006-06-09 09:26:24 · answer #4 · answered by EyasOo 2 · 0⤊ 0⤋
Pascal's triangle probably would help.
There are 45 ways to have 8 heads and 968 combinations total, if that helps you any.
2006-06-09 04:21:18 · answer #5 · answered by the Politics of Pikachu 7 · 0⤊ 0⤋
probabililty = favourable outcome / total outcome ie. 8/10 = 4/5
2006-06-09 04:15:05 · answer #6 · answered by Abhishek_Cool 2 · 0⤊ 0⤋
(8/20)*(9/20)*(10/20)
2006-06-09 04:19:32 · answer #7 · answered by babloo 3 · 0⤊ 0⤋
(10C8)*(1/2)^10
2006-06-09 04:29:04 · answer #8 · answered by sankardivya1 2 · 0⤊ 0⤋