O-LevelAdditional MathematicsLogarithmic and exponential functions4037/12 · May/June 2018 · Q75 Marks
A population, B, of a particular bacterium, t hours after measurements began, is given by B = 1000e^(t/4).
- (i)Find the value of B when t = 0.[1]
- (ii)Find the time taken for B to double in size.[3]
- (iii)Find the value of B when t = 8.[1]
Mark scheme
Marking points from the official mark scheme (May/June 2018). The mark or mark type is shown in brackets.
- B1 1000
- B1 2000=1000e^(t/4)
- M1 For (1/4)ln k or ln k¹, k > 0 t=4ln2, ln16
- A1 2.77
- B1 B = 1000e² = 7389, 7390
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