Victor Schröder's solution: Challenge 10

var delay = 60,
    position = 0,
    divs = $('div');

setTimeout(makeBlue, delay);

function makeBlue(){
    divs.eq(position).blue();
    divs.eq(position + 5).blue();
        setTimeout(function(){
            position++;
            if(position >= divs.length){
                position = 0;
            }
            setTimeout(makeBlue, 500);
        }, 100);
};