A few days ago
Anonymous

Help me on another probability question, please?

Help me on this, please?

And show how to get the result? :/

Thank you..

I flip an unfair coin 3 times. The probability of getting at least one head is 218/343. What is the probability of getting all heads?

Thank you. <3

Top 2 Answers
A few days ago
gateach

Favorite Answer

If the probability of getting at least one head is 218/343 then this includes every possibility except getting 3 tails. That probability would be 125/343. Take the cube root of this and you get 5/7 which is the probability of getting a tail on one flip. Then the probability of getting a head on one flip would be 2/7. Multiply this times itself 3 times and you get 8/343 (the probability of getting all heads).
0

A few days ago
astatine
Let the prob of getting a tail be p

The prob of getting 3 tails is p^3

Hence the prob of getting at least 1 head is:

1-p^3 = 218/343

p^3 = 1 – 218/343 = 125/343 = 5^3/7^3

prob of a head is 1-p which works out to 2/7

So prob of 3 heads is this cubed.

0