Typical costs: Having a contractor level and prepare the area then pour a concrete slab ranges from $1,000-$2,000 for a 10x20-feet; $4,000-$6,000 for 80x20-feet; and $5,000-$10,000 for 100x100-feet. Smaller projects cost more per square yard because of minimum travel, labor and equipment costs.
What makes yogurt - well, yogurt? The words live and active cultures refer to the living organisms, Lactobacillus bulgaricus and Streptococcus thermophilus, which convert pasteurized milk to yogurt during fermentation. Note that the milk is pasteurized before culturing to remove any harmful bacteria.
Look for your yogurt at a health food store (or in the health food section of any grocer that has one), the brands you find there typically have three different strands of active culture. Better yet, try kefir. It is similiar in taste to yogurt, but has an impressive ten active live cultures.