takes 1 hour and 21 minutes for a 2.00 mg sample of radium-230 to decay to 0.25 mg. What is the half-life of radium-230?

Mozart lenses inc. recently introduced seelites, a thinner lens for eyelasses. of a sample of 800 eyeglass wearers, 246 said they would purchases their next pair of eyeglasses with the new lenses. lenses inc. estimates that the number of people who purchase eyeglasses in a year is 1,700,000. most eyeglasses wearer buy one new pair of eyeglasses a year. what is the annual sales potential for the new lenses.

School has 204 sixth grade students. if the sixth grade is 30% of the total school, how many students are in the middle school?

One hectometer is a) 1/1000 of a meter. b) 1/100 of a meter. c) 10 meters. d) 100 meters. e) 1000 meters.