Element X is a radioactive isotopes such that every 24 years, it’s mass decreases by half. Given that the initial mass of a sample of element X is 70 g, how long would it be until the mass of the sample reach 61 g, to the nearest 10th of the year?

The longer leg of a 30° 60° 90° triangle is 16 times square root of three how long is a shorter leg

Set $r$ is a set of rectangles such that (1) only the grid points shown here are used as vertices, (2) all sides are vertical or horizontal and (3) no two rectangles in the set are congruent. if $r$ contains the maximum possible number of rectangles given these conditions, what fraction of the rectangles in set $r$ are squares? express your answer as a common fraction.

Which equation can be used to measure the density of water in a spherical water tank? let w represent the number of water particles within the region.