[Rise]

failure,

var mass = [107,89,102,108,94,72,70,84,112,73];
var nBig = 0, mBig = 0, aBig = 0;
var nNorm = 0, mNorm = 0, aNorm = 0;
	
for (var i = 0; i < mass.length; i++) {
	if (mass[i] > 100) {
		nBig++;
		mBig += mass[i];
	} else {
		nNorm++;
		mNorm += mass[i];
	}
}
aBig = Math.round(mBig / nBig);
aNorm = Math.round(mNorm / nNorm);
	
alert('Ср.масса больших: ' + aBig + '\nСр.масса обычных: ' + aNorm);