Question 1197161
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A coin is loaded so that heads is three times as likely as the tails. For 3 independent
tosses of the coin find the pmf of the total number of heads realized and the probability of
realizing at most 2 heads.
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<pre>
"The Head is three times as likely as the tail" means that the probability of getting
head is 0.75, while the probability of getting tail is 0.25.


So you have a binomial distribution problem with n= 3 trials and the probability
of each individual success p= 0.75.


Now go to web-site https://statisticshelper.com/binomial-probability-calculator 


    +----------------------------------------------------------------------+
    |   It contains free of charge calculator, which computes the entire   |
    |       probability mass function, as soon as you input there          |
    |                      input parameters.                               |
    +----------------------------------------------------------------------+


The input parameters, as I just said, are n= 3 (number of trials) and p= 0.75 (individual success).


Not only the calculator will give you probability mass function as a table,
but, in addition, it provides step-by-step complete and detailed explanation to each step.


So, it makes me free from doing this routine and many-times-repeating job 
to explain everything from the beginning to the end each day, as I see such problem arrived to the forum.
</pre>

Happy learning (!)