Question

Element X decays radioactively with a half life of 9 minutes. If there are 760 grams ofElement X, how long, to the nearest tenth of a minute, would it take the element todecay to 19 grams?y = a(.5)Answer:

Answer 1

`y=a(0.5)^{(t)/(h)}`
`19=760(0.5)^{(t)/(9)}`
`(19)/(760)=(0.5)^{(t)/(9)}`
`0.025=2^{(-t)/(9)}`
`\log _20.025=(-t)/(9)^{}`
`t=-9\cdot\log _2(0.025)`
`t=47.89\approx47.9`