# Probability involving stock market help pls

I

#### -illuzion-b18c1

##### Guest
Stock A and stock B.
Every day the price of stock A will either increase by 1 dollar with probability 0.6 or decrease by one dollar with probability 0.4. Similarly stock B will either increase by 2 dollars with probability 0.55 or decrease by two dollars with probability 0.45.

1. If, at the beginning, the prive of stock A was 100 dollars and that of stock B was 120 dollars, what is the (approximate) price distribution of stock A and B after 100 days?

Mu-stockA=.2 multiply by n=100 so Mu-stockA=20
Mu-stockB=20 as well

using this equation i found Stand.Dev.
Var^2=SUM( (Xi-mu)^2 * p(Xi) ) ....i then multiplied variance by n and took the entire square root to get...
StandDev.-stockA=9.7979
StandDev.-stockB=19.8997

2. Compute the probability that, after 100 days, the price of stock A will be less than than its initial price. Do the same for stock B.