Yes, 0 or no ups in a day would be the remaining probability (i.e. Probability of failure) Since probability of having a up = 0.5 Probability of having no ups ( either 0 or down) = 0.5 That’s the whole premise binomial prob equation is based on.
Also, I took 2020 n 2121 set… and in my set it asked for prob of it goin up 4 days outta 5… From what you said LongOnCFA, seems like u had a different set…
I just used 0.5^4 * 0.5 * 5 for the probability of going up not more than once in 5 days ( I took set 1010/1111). Was that correct?
Chance of 0 rises in 5 days: 3.125% Chance of 1 rises in 5 days: 15.625% Chance of 2 rises in 5 days: 31.250% Chance of 3 rises in 5 days: 31.250% Chance of 4 rises in 5 days: 15.625% Chance of 5 rises in 5 days: 3.125% The sum of the first two probabilities is 18.75%.
Si Senor!
so , i guess i got that one wrong 
so we had to sum the prob of it going up 0 days and 1 day? sh****TTT i did not do that… i thought it was just the 1 day… so for what i did was the prob of going up exactoy one day… not the prob of going up no more that one day?