0 votes 0 votes Suppose a radioactive substance decays according to the equation $y=2000e^{-0.75t}$, where $y$ represent the mass in grams after $t$ hours. How much of $2$ milligram will remain after $8100$ years? Quantitative Aptitude compound-growth + – Hailemariam asked Aug 4, 2022 recategorized Aug 9, 2022 by Arjun Hailemariam 430 views answer comment Share Follow See all 2 Comments See all 2 2 Comments reply ankitgupta.1729 commented Aug 4, 2022 reply Follow Share The given equation shows the exponential decay of a radioactive substance. In general, we can write the equation as $N= N_0 e^{-\lambda t}$ where $t$ represents the time, $\lambda$ is decay constant, $N_0$ is the initial quantity of the radioactive substance at $t=0$ and $N$ is the remaining quantity after time $t.$ So, here, initial quantity is given as $N_0 = 2 \ mg =2 \times 10^{-3} g,$ $\lambda= 0.75$ (Taking it from the given equation because it is not given specifically) and $t= 8100 \ years = 8100 \times 365 \times 24 \ hours$ (Assuming every year has 365 days and each day has 24 hours) So, remaining quantity (N) $= 2 \times 10^{-3} e^{-0.75\times 8100 \times 365 \times 24 } $ grams 1 votes 1 votes Hailemariam commented Aug 4, 2022 reply Follow Share Tnks alot 1 votes 1 votes Please log in or register to add a comment.