# 2Coins probability of Heads-tails in 40 tosses? HELP!

2 coins are tossed at the same time There are 3 colums in a chart

3)Tails-Tails

the coins were tossed 40 times simultaneously.

What was the probability that heads-tails (or tails-heads) would appear? Show calculations.

(HINT: The probability of these two combinations must be added together because they were recorded together.)

Im thinking its 2/4 but not sure, and dont know what to show as calculations.
PLEASE HELP ME! offtopic said:
(0_o) youve created 3 topics about this...you need to stop before you get banned, and to my observation this isnt the first time

but im not so great with it either, but wouldnt it be 1/3 chance for all?

BobG
Homework Helper
aisha said:
2 coins are tossed at the same time There are 3 colums in a chart

3)Tails-Tails

the coins were tossed 40 times simultaneously.

What was the probability that heads-tails (or tails-heads) would appear? Show calculations.

(HINT: The probability of these two combinations must be added together because they were recorded together.)

Im thinking its 2/4 but not sure, and dont know what to show as calculations.
PLEASE HELP ME! Yes, you're correct.

You have a 50% chance of coin 1 coming up heads. If coin 1 comes up heads, you have a 50% chance of coin 2 coming up heads. .5 * .5 gives you a 25% chance of both coins coming up heads.

If you do the same for each combination, you wind up with a 25% chance of each combination coming up. Since the coins are tossed simultaneously, you don't know if you have heads-tails or tails-heads. So you add the probabilities for both combinations together.

jtbell
Mentor
BobG said:
Since the coins are tossed simultaneously, you don't know if you have heads-tails or tails-heads. So you add the probabilities for both combinations together.

Unless, of course, you have two different coins (say a quarter and a loonie) and it matters which one is which. Then you would consider loonie-heads and quarter-tails as a different outcome from loonie-tails and quarter-heads, each with 25% probability.

can u show me what the calculation would look like BOB? I understand what your saying but not 100% sure.

GCT