Kaplan Page 136 #19
If 3 coins are tossed simultaneously, what is the probability of getting exactly 2 tails?
The answer is 3/8. Instead of listing all the cases, is there a faster way to solve this problem?
Thanks in advance
Kaplan Page 136 #19
If 3 coins are tossed simultaneously, what is the probability of getting exactly 2 tails?
The answer is 3/8. Instead of listing all the cases, is there a faster way to solve this problem?
Thanks in advance
Every coin flip has a $\displaystyle \frac{1}{2}$ chance of turning up heads or tails.
You can have T, T, H or T, H, T or H, T, T
Each of these 3 outcomes has a probability of $\displaystyle \frac{1}{2} \times \frac{1}{2} \times \frac{1}{2} $
So probability for exactly 2 tails for 3 coin tosses = $\displaystyle 3 \left( \frac{1}{2} \right)^3 = \frac{3}{8}$