A radioactive substance has a half-life of 5 million years. What is the age of a rock in which 25% of the original radioactive atoms remain? You must show your work or explain how you came up with your answer for full credit.

Facial shaving brushes are either bulb-shaped or fan-shaped. an experiment is to be conducted to determine whether the lather thickness is the same for both types of shaving brushes. in previous studies, it was determined that shaving brush size (small, medium, large) is associated with lather thickness, but shaving brush type (wolf whiskers, maggard razors, frank shaving, and so on) is not associated with lather thickness. how could the experiment best be conducted? by blocking on shaving brush size by blocking on shaving brush type by blocking on shaving brush shape by blocking on lather thickness without blocking

Who wants free points + brainliest? answer this question correctly and you shall receive if you're caught driving with you could be punished with up to a year in jail and be fined up to $1,000. a. a suspended driver license or license plate b. an intoxicated minor passenger c. headphones covering both ears d. a broken taillight or headlight

Briefly explain how one development from the period 1861 to 1865 not directly mentioned un the excerpts supports mcpherson's argument