Question

Anyone up for probability ?
how many times must a fair coin be tossed so that the probability of at least one head exceeds 0.9

Answer 1

btw its bionomial distribution

Answer 2

Let n be the number of times a coin is tossed. Find an expression for the probability of at least 1 head for n tosses (use complimentary events to do so). That value needs to exceed 0.9. Then find n.

Answer 3

I would do 1-P(no heads) :p

Answer 4

darling u just googled this question and found this answer even i saw that answer thousand times on bored of studies

Answer 5

thnx for trying though lol

Answer 6

u think @kc_kennylau i tried log too but seems to not work

Answer 7

1- 1/2 = 1/2 but the answer is 4

Answer 8

P(at least one head)
=1-P(no heads at all)
=1-P(0.5^n)

Answer 9

sorry it should be 1-0.5^n

Answer 10

yea its quiet tricky prbably gonna ask my teacher on monday then post answer

Answer 11

\[\large1-0.5^n>0.9\]\[\large0.5^n<0.1\]

Answer 12

\[\large\log_{0.5}{0.5^n}<\log_{0.5}0.1\]\[\large n<\log_{0.5}0.1\]

Answer 13

3.32192809488736234787031942948939017586483139302458061205475639581593477660862521585013974335937015509965737171025025182...

http://www.wolframalpha.com/input/?t=crmtb01&f=ob&i=log_0.5%200.1

Answer 14

Round it up and you get \(\Huge4\) :)

Answer 15

hahah thnx man but to round it off to 4 u need the value at least to be above 3.5

Answer 16

even i got that answer

Answer 17

well I said round it \(\large\mbox{up}\) not round it \(\large\mbox{off}\) :)

Answer 18

sorry brb

Answer 19

hahah ok i didnt read it properly sorry

Answer 20

it's not your fault :)

Answer 21

but thank u so much for ur time

Answer 22

oh it's my duty :)