Based on the graph, what can you say about the amount of time it will take for the strontium-90 to decay completely?

It'll take an infinite amount of time.

The function seems to be f(x)=100(1/2)^x, which won't ever result in 0.

c) 50% there are four chromosomes. after crossing over, 2 of the four have been changed. that means any gamete has a 2 in 4 chance or 50% chance of receiving the mutated chromosome.