A substance has an initial mass of

MATHEMATICS · Single correct · A Level · Mathematics · Exponentials and logarithms · Exponentials and logarithms

Problem

120\text{ g}

. Ten days later its mass is measured at

80\text{ g}

. Assuming exponential decay, what is the predicted mass (in grams) after a total of

25

days? (a)

65.5

(b)

36.3

(c)

43.6

(d)

54.4