Question

there are 13 girls and 15 boys in a line if one student in choosen at random then find the probability that he is a boy

Answer 1

total student =15+13=27
probability=favourable outcomes÷ total outcomes
= 15/27 or 5/9

Answer 2

let the 13 girls be G1 G2 G3 ...G13.
and let the 15 boys be B1 B2 B3...B15
S={G1,G2,G3,G4,G5,G6,G7,G8,G9,G10,G11,G12,G13,B1, B2,B3, B4, B5 B6,B7, B8, B9,B10, B11, B12,B13, B14,B15}
n(S)=28
let A be the event that the student chosen will be a boy
A={B1, B2,B3, B4, B5 B6,B7, B8, B9,B10, B11, B12,B13, B14,B15}
n(B)=15
P(B)= n(A)/(S)
= 15/28 ..
..the probability is 15/28