Question

Probability maths question . need help asap

Answer 1

11 beads: 7 red , 4 white

`probability = (the \: desired \: outcome)/(all \: possible \: outcomes)`

we calculate the desired outcome using combinations of 11 beads. we know that we can select "r" beads from "n" beads in this way:

`\binom{n}{r} = (n!)/(r!(n - r)!)`

where:

`n! = n * (n - 1) * ... * 3 * 2 * 1`

so the probability is:

`p = \frac{ \binom{7}{1} * \binom{4}{1} }{ \binom{11}{2} } = (7 * 4)/(55) = (28)/(55)`