To find the E(X) expected value, you come up with the different probabilities for each outcome
your set of outcomes after 3 tosses would be = {HHH, HHT, HTH, THH, HTT, THT, TTH, TTT} where H is heads and T is tails
Each element has a probability of 1/8 so let x represent number of tails
$Probability(x)=P(x)\\P(0)=\frac{1}{8} \\P(1)=\frac{3}{8} \\P(2)=\frac{3}{8} \\P(3)=\frac{1}{8}$
The E(x)=Summation (x times P(x))
$E(X)=(0)(0.125)+(1)(0.375)+(2)(0.375)+(3)(0.125)=1.5$
Now which probability is 1.5 tails? None, so it is either 2 tails or 1 tails
So you can expect to lose money in 1 game
But as you play more games the probability of getting 3 tails becomes more and more likely, so you can expect to win in a 100 games

8 0

3 years ago

Alexandra earns $125 from her paper route each month, but she spends about $20 each month on personal expenses to pay for a scho

SVEN [57.7K]

125 per month-$20 per month expences=105 savings each month
800/105= number of months needed to save

Answer 7.6 (rounded) roughly about 7 and a half months. If shes paid monthly, then 8 montjs needed

8 0

3 years ago