If a radioactive nuclide has a half-life of 1.3 billion years, and it is determined that a rock contains 12.5% of its original amount of this nuclide, about how old is the rock?

I would figure this out slowly. So the percentage would be 25 2.6 billion years ago. That would leave it at 50 percent 5.2 billion years ago. If you double that 50 percent to get 100% and double the 5.2 billion years you get 10.4 billion years. This would make the answer, the rock is 10.4 billion years old

The independent variable is the type of music.the dependent variable is the pulse rate.the intervening variable is the age of the subject.if the mother does not like rock, her pulse is likely to not increase.the same might be true for the sister.the friend may like rap and gets excited.to establish cause/effect relationship, all of the subjects must be consistent.hope i .

The correct answer is b) false