Maths about probablity , pls help me

by drawing tree diagram
we know that all the probability which would happen = 2^60 = 1.152921505x10^18
by using nCr
since there are 60machines
so n = 60 and r is the number we want to find
60C(r+(r+1)+...+60) = 1.152921505x10^18 x 0.1 =1.152921505x10^17
since
60C(35+36+...+60) = 1.412679522x10^17
and 60C(36+37+...+60) = 8.935251419x10^16
so the ans will be 35 or 36



P.S if the ans is wrong ,then the ans may be 60*0.1 = 6(just guess)

Did the question provide the value of mean or standard deviation or variance?
Or what kind of distribution is it, normal? Possion?