You need to first split your 3 criterias. Calculate how many females over total people. I would use

Code:

`countif(A1:A99;"Female")/count(A1:A99)`

formula if people sex was in column A, from row 1 to 99. In another cell, calculate how many live in London using the same formula but with London. Third cell would be

Code:

`Countif(C1:C100;">=495")/count(C1:C99)`

if net salaries are in column C. You then multiply each percentage to get the probability it happens. You can calculate everything at once multiply directly but it is good to check each result the first time.