A certain radioactive substance has a half-life of 5 hours. Find the time for a given amount to decay to one-tenth of its original mass

Question

anonymous · Answer

We want to find the half life so the base of the exponential equation should be 0.5 for simplicity. We also have to divide by the half life (t), and x represents the time.
$$y=0.5^{x/t}$$

Do you think you know what to do now that you have this equation?

mony01 · Answer

not really

mony01 · Answer

@Riddellikins so x is 5 and what is t?

wolf1728 · Answer

We'll call beginning amount 100% and ending amount 10% elapsed time = half-life * log (beg amt/end amt) / log 2 elapsed time = 5 hours * log (100/10)/0.3010299957 elapsed time = 5 * 1/0.3010299957 elapsed time = 5 * 3.3219280945 elapsed time = 16.6096404724 hours formulas and calculator here: http://1728.org/halflife.htm

wolf1728 · Answer

mony01 you get the same answer?