Mathematics 1 Deneme Sınavı Sorusu #1144666

What is the half-life of a radioactive substance if 90% of the initial amount remains at the end of 25 years ?


50 (ln 0.5) ln 0.9

75 (ln 0.9) / ln 0.5

25 (ln 0.5) / ln 0.9

100 ln (0.5 / 0.9)

150 ln (0.9 / 0.5)


Yanıt Açıklaması:

Q(t) = Q0 ek t ; 0.9 Q0 = Q0 ek 25 ; ln 0.9 = k 25 ; k = (ln 0.9) / 25 ; 0.5 Q0 = Q0 e((ln 0.9) / 25) t ; ln 0.5 = ((ln 0.9) / 25) t ; t = 25 (ln 0.5) / ln 0.9 Correct answer is C.

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