A medical scientist has a 15-gram sample of I-131 and would like to its half-life, in days. He also knows that k = 0.0856.

N = N0e -kt

N0 = 15 grams

N = 7.5 grams

k = 0.0856

t = ?

Find the half-life, in days, of I-131 using the information at the left. Round your answer to the nearest tenth.

Question

A medical scientist has a 15-gram sample of I-131 and would like to its half-life, in days. He also knows that k = 0.0856.

N = N0e -kt

N0 = 15 grams

N = 7.5 grams

k = 0.0856

t = ?


Find the half-life, in days, of I-131 using the information at the left. Round your answer to the nearest tenth.

photon336 · Answer

Please re-arrange the formula for t 

$$N = N_{0}e^{-kt}$$

$$\frac{ N }{ N_{0} } = e^{-kt}$$

$$\ln(\frac{ N }{ N_{0} }) = \ln(e^{-kt})$$

$$Ln(\frac{ N }{ N_{0} }) = -kt $$

$$-k*\ln (\frac{ N }{ N_{0} }) = t $$

anonymous · Answer

Ok

anonymous · Answer

And don't I need to divide 7.5 abd 0.0856

anonymous · Answer

And*

photon336 · Answer

$$-8.56*10^{-2}*\ln (\frac{ 7.5 }{ 15 }) = t$$