And we are done.There is a need to 're-engineer' the way statistics is taught in the academe as technological development has greatly influenced the pedagogy of most disciplines. So the probability of flippingĮxactly 2 heads is equal to the 3 outcomes with 2 headsĭivided by the 8 possible outcomes, or 3/8. If you didn't say exactly, then maybe 3 heads, when youįlip 2 heads, so we have to say exactly 2 heads. So the probability of flippingĮxactly 2 heads- And the word exactly is important, because Outcomes involve flipping exactly 2 heads? Let's see, that's all tails. We could get tails,Ħ, 7, 8 possible outcomes. Of the different possible ways that we can flip 3 coins. Probability, a good place to start is just to think about all Of flipping exactly two heads on 3 coins. ( Its better to remember this rule: divide the final probability by the number of repeating characters' factorials. If u have doubts, check out Sal's basic permutation videos.) So the probability of all three events happening in any order is 1/2* 1/2*1/2* 3!Ħ. Hence three events can be arranged among themselves in 3! (3 factorial) ways. Now remember, these three events can occur in ANY order. and step 2 AND step 3 happening is 1/2 * 1/2 * 1/2.

probability of tail in third toss is 1/2.Ĥ. probability of head in second toss is 1/2.ģ. probability of getting a head in first toss is 1/2.Ģ. If u understand the concepts, u can solve this problem in a single step.ġ. Guys, I'll try to give you a step-wise template so that you can attempt all similar problems without wasting time.

Khan academy elementary statistics