Problem 403. Einsteinium-253 decay

Created by Bruce Raine

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Radioactive Einsteinium-253 has a half-life of 1,768,608 seconds. Given 1000mg of Einsteinium-253 at t=0 days, how much is left after 50 days?

EX: >> decay(50)

184

HINT: find k, then decay(50)

Use: decay(t)=10^3*e^(k*t)

NB: make sure you round your answer up to the next highest integer.

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215 Solutions
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Last Solution submitted on Aug 29, 2019

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Problem Comments

5 Comments

5 Comments

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Alfonso Nieto-Castanon on 25 Feb 2012

guess you mean minutes instead of seconds?

Bruce Raine on 25 Feb 2012

Hi, no I do mean seconds if you are referring to the constant, 29,476.8

Bruce Raine on 25 Feb 2012

I have readjusted it now so it is the correct value.

Rick Rosson on 25 Feb 2012

I believe you are always rounding up to the next highest integer rather than rounding to the nearest integer. In other words, you are using the ceil() function, not the round() function.

Bruce Raine on 25 Feb 2012

Hi Rick, yes you are quite right. I have made the correction as above. Thanks for your valuable input.

Solution Comments

Solution 51323

2 Comments

2 Comments

@bmtran (Bryant Tran) on 25 Feb 2012

I believe your second test case is incorrectly rounding.

Bruce Raine on 25 Feb 2012

Yes, you were right with my earlier incorrect "note well" remark but now with corrected remark in place this test is valid. Sorry if it has put you off a bit. I guess other issues may come to light as well but I hope not.

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Problem Tags

half-life isotope natural log radioactive decay