Each penny independently has a 50% chance of landing on heads, one-in-two.
So our possibilities for one flip are:
H
T
For two flips:
HT HH
HT TT
Meaning that for two flips we're down to 1/4. 1/2 of the time the first one comes up heads, and 1/2 of those times, the second one will do. 1/2 * 1/2 = 1/4The third flip will be the same way:
HTH HTT HHT HHH
HTH TTT HTH TTH
Again, only in the case where we already have 2 heads is it possible to get another heads and still have all heads. Therefore, only half of the ones where there were already two heads will be three heads.
1/2 * 1/2 * 1/2 = 1/8 of the time. There is a 12.5% chance of all heads.
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What is the chance of it landing on heads twice in a row?
The probability of the first coin landing heads is half (or 1/2). Similarly, the probability of the second and third coins landing heads are also 1/2 in each case. Therefore, the probability of having three heads is: (1/2)(1/2)(1/2) = (1/8)
1/8. The probability of flipping a coin three times and it landing on head is 1/2, as a coin only has two sides. You flip a coin three times, therefore the answer is (1/2)^3 = 1/8.
Each time you flip a coin, the probability of a given outcome is1/2. This is multiplied by itself every time you repeat the flip. three times: 1/2 * 1/2 * 1/2 = 1/8 decimal: .125The probability of a fair coin landing heads up is: P(H) = 1/2The probability of a fair coin landing heads up three times is: P(HHH) = (1/2)3 = 1/8= 0.125 = 12.5%One eighth or 12.5%
12.5%