The number of adults living in homes on a randomly selecyed city blocks is described by the following probabilitydistribution. Numer of adults, x = 1,2,3,4 or more.
probability, P(x) = 0.25,0.50,0,15,.
What is the probability that 4 or more adults reside at a randomly selected home?

- 70

this is the answer for you hope it

ending amount = beginning amount / (2^n)

where "n" = number of half-lives (or elapsed time / half-life)

ending amount = 50 mg / (2 ^10 / 5.3)

ending amount = 50 mg / (2 ^ 1.8867924528)

ending amount = 50 m / 3.6981210597

ending amount = 13.5203794557 mg

or about 13.5 mg remain

source:  

arc length = radius * x ( in radians)

6 * pi = 18 * x

divide by 18 on each side

6 pi / 18 = x

pi/3 = x

the angle is pi / 3 radians

or   60 degrees