1.9.17 Concavity and the second derivative (A-level only)

The population of a luminescent algae colony, $P$ , measured in thousands, is modelled by the function

20\sqrt{t} + 25, \quad t > 0

where $t$ is the time in hours since the colony was first observed.

Determine the values of $t$ for which the population is exactly 9 thousand.

[3]

Find the value of $t$ for which $d2Pdt2=527\dfrac{d^2P}{dt^2} = \dfrac{5}{27}$ .

[4]

1.9.17 Concavity and the second derivative (A-level only) Questions

The population of a luminescent algae colony, $P$ , measured in thousands, is modelled by the function

20\sqrt{t} + 25, \quad t > 0

where $t$ is the time in hours since the colony was first observed.

Determine the values of $t$ for which the population is exactly 9 thousand.

[3]

Find the value of $t$ for which $d2Pdt2=527\dfrac{d^2P}{dt^2} = \dfrac{5}{27}$ .

[4]