Mother, father and son line up at random for a family picture E: son on one end, F: father in middle

Solution:

We assume that denote mother, denote father and denote son.

Then, the sample space for the given experiment will be:

S= MFS, SFM, FSM, MSF, SMF, FMS}

The events given are E: Son on one end

& F: Father in middle
Sample space of the following are:

and

The probability of the event,

Now, we know that by definition of conditional probability,

Now by substituting the values we get