Th answer is 5 because 31% of 15 is 4.65
Answer:
x=50
Step-by-step explanation:
Answer:
3Y - 4X - 4
Step-by-step explanation:
The equation tells you the half-life is 30 years. In 90 years, 3 half-lives will have passed, so the decay will be to (1/2)^3 = 1/8 its original level. Radiation will not have decayed to 1/10 its original level in 80 years. The area will be unsafe in 2067.
f(x) = 1000·0.5^(x/30)
f(80) = 1000·0.5^(80/30) ≈ 157.5 . . . . kilograms
