The half-life of a radioactive substance is the average amount of time it takes for half of its atoms to disentegrate. suppose you started with 200 grams of a substance with a half-life of 3 minutes. how may minutes have passed if 25 grams now remain? explain your reasoning.

Me answer number 3plz explain how you do it

Which choice represents the sample space ,s for this event

Last year, a state university received 3,560 applications from boys. of those applications, 35 percent were from boys who lived in other states. part a)how many applications did the university receive from boys who lived in other states? part b)applications to the university from boys represented 40percent of all applications. how many applications did the university receive in all? i don't how to do part b so me and plz tell how you got your answer