No it is not. You have no source to prove your word for a very simple reason, it's total bulshit. Find me just ONE study talking about 15% muslim, just ONE.
Cause I can give you as much as you want claiming the 5% are still reliable.
You will not be able to give any "reliable" proof to backup your claims, because racial and religious statistics are banned in France. No matter how many sources you cite, all of them will be just assumptions rather than real population count.
There has been only one population count according to racial origin in France during the last 100 years. It was a study conducted by the French medical association, on the prevalence of sickle-cell anemia. This particular disease affects only people having Arab, Black, Turkish and Indian descent. So the medical association tabled data on births, where at least one of the parent is from these backgrounds.
This is what they found: 34.44% of newborns in France in 2012 were non-White.
Data from 2013:
http://1.bp.blogspot.com/-EhD4yaZnnN8/VEVCZ22G3fI/AAAAAAAAAF8/Zng9za4gdFk/s1600/National%2BScreening%2BTests%2Bon%2BSickle%2BCell%2BDeasease%2Bin%2BNewborns%2C%2BFrance%2B2005-13.jpgData from 2014:
https://bloodyshovel.files.wordpress.com/2015/12/73akbau.png?w=630Damn you're really tiring...
First it's not about race but religion.
Second religion stats are allowed in France, they're just not done by the government, the National census is not taking it into account that's all.
Third What I provided are not just "assumptions" they're studies that have been proceeded by asking people. Of course it's not 100% reliable as it's a poll, but when ALL the polls that have been made give you the same result it's pretty logical to assume this result might be the good one.
Fourth your study was conducted on a selected kind of children not on all the population.
Fifth even if your study was correct you're talking about non white I was talking about Muslims. France being a former colonial power it seems rather logical to have a strong portion of the population being black, doesn't mean they're Muslims.
Sixth you still never provided ANY kind of source or proof to back your words. You're just giving me figures coming directly from your ass...