Yaz birthcontrol has 4 inactive pills at the end of each pack if I have sex during those pills will I have a normal riskof getting pregnant

No

EDIT OK I'll explain some more but I need to find some graphs first

Back again, found a good one.
Graph (http://images.google.co.uk/imgres?imgurl=http://www.nature.com/eye/journal/v18/n5/images/6700713f1.jpg&imgrefurl=http://www.nature.com/eye/journal/v18/n5/fig_tab/6700713f1.html&h=652&w=600&sz=104&hl=en&start=1&um=1&tbnid=w-0_a_gejeiIcM:&tbnh=138&tbnw=127&prev=/images%3Fq%3Dcontraceptive%2Bpill%2Bhormone%2Bcycl e%26um%3D1%26hl%3Den%26safe%3Doff%26client%3Dfiref ox-a%26rls%3Dorg.mozilla:en-GB:official%26sa%3DG)
The blue line is your normal oestrogen levels and the green your progesterone. What the pill does is mask your normal oestrogen levels so that you don't get that big spike in the middle. When it spikes like that you ovulate and therefore you can get pregnant. The contraceptive pill also contains progesterone which thickens the cervical mucus (amoungst other things) and aids pregnancy prevention.

The dummy pills won't affect your chances of getting pregnant providing you took the others correctly and there was nothing affecting your metabolism of your pill. This is because you would not have ovulated, no egg = no baby.

Of course no method of contraception is 100% effective; there are a myriad of reasons you might ovulate anyway. But the dummy pill won't affect this.

Many contraceptive pills don't even have dummy pills but instead just instruct a break. It depends on the type and manufacturer.