SOLUTION: Of the members of a Boy Scout troop, 15% have received the first aid merit badge. If 40 boy scouts are selected at random, find the probability that four or more will have the firs

It is a binomial distribution probability problem.

    - number of trials        n =  40;
    - number of success trial k >=  4;
    - Probability of success on a single trial p = 0.15.



We need calculate  P(n = 40; k >= 4; p = 0.15).      


To facilitate calculations, I use an appropriate online (free of charge) calculator at this web-site 

https://stattrek.com/online-calculator/binomial.aspx


It provides nice instructions  and  a convenient input and output for all relevant options/cases.


    P(n = 40; k >= 4; p = 0.15) = 0.869831,   or   86.9831%  (rounded).       ANSWER