If two brown-eyed parents have produced three blue-eyed sons and if they have another child, it's likely their next child will be brown-eyed. Both parents have a recessive allele for blue eyes, so it is a 75 percent chance the next will be brown-eyed.
Hope that helps. -UF aka Nadia
Osteoporosis refers to an ailment characterized by reduced bone mass and loss of bony tissue that may lead to weak and fragile bones. In an experiment, Dr. Travis tested the influences of the consumption of calcium on osteoporosis, the condition that results in enhanced chances of bone fractures.
In the given experiment, the amount of calcium is the independent variable, and the risk of bone fractures could get changed with the amount of calcium consumption.