the only combination which does not produce heads at least once it tails twice. the odds of getting tails twice is 0.5*0.5=0.25 so the odds for getting heads at least once is 1-0.25=0.75 or 75% or 3/4.
3 to 1
3 over 4 , or 8th quared
Saying that the odds of something occurring are a to b (or a:b) means that we expect the event to occur a times for every b times it does not occur. For instance, the odds of drawing tails on a coin flip are 1 to 1, so if we repeat the experiment a very large number of times, we will have 1 occurrence of "tails" for every occurrence of "heads". The odds of getting a 5 on a dice roll are 1:5, and so on.
The answer I'm editing says the odds are 1 in 8. This is true only if you actually mean the probability of getting 3 tails in a row, rather than just 3 of either heads or tails in a row. In mentioned case, the first flip doesn't matter which side it lands on, just the proceeding two flips do. So, the odds of flipping a coin three times with the same outcome are 1 in 2^2 or 1 in 4. The odds of flipping three tails in a row are 1 in 2^3 or 1 in 8.
3 out of 8
if you rollid a die once the odds of getting less than four would be 3/6 or 50%.
There are 4 possible outcomes, HH, HT, TH, TT. If we assume the odds of tossing heads or tails on any toss is 1/2 (50:50) the odds of tossing heads twice in a row is 1/4 (or 25%).
If the coin is fair, thenThe chance of tails on the 1st toss is 50% (1/2).The chance of tails on the 2nd toss is 50% (1/2).The chance of tails on the 3rd toss is 50% (1/2).The chance of tails on the 4th toss is 50% (1/2).The chance of tails on the 5th toss is 50% (1/2).The chance of tails on the 6th toss is 50% (1/2).The probability of getting all of them is (1/2) x (1/2) x (1/2) x (1/2) x (1/2) x (1/2) = 1/64 = 1.5625 % .The odds are 63 to 1 against.
The greater odds are on getting willingly robbed at a casino.