probability . Help.

Question

An experiment yields one of five sample data points : A,B,C,D, and E. If P(A)=P(B)=P(D)=P(E)=.1, whats P(C)?

Answer 1

Total probability has to be equal to 100%, or 1.

What this means is

P(A)+P(B)+P(C)+P(D)+P(E)=1

Plugging in the values you know

0.1+0.1+P(C)+0.1+0.1 = 1

0.4+P(C)=1

P(C)=0.6