1. For the following flows and a GCRA(100, 500), give the conformant and non-conformant cells. Times are in cell slots at the link rate. (a) 0, 100, 110, 12, 130,….

## What was the time duration of the entire experiment (from the introduction of the mould until its disappearance)?

A biochemist is testing the effect of a new antibiotic on a particular

mould growing in a petri dish. Without the antibiotic the mould grows as a

circular patch with the radius increasing with time according to r = 0.5t cm

where t is measured in hours since the mould was introduced to the petri dish.

The area of the mould is given by A = pr2

, the area of a disc of radius r. When

the radius of the disc reaches 2cm the biochemist introduces the antibiotic. This

causes the radius of the disc to reduce according to r = 2 –

v

t cm where t is

measured in hours since the antibiotic was introduced.

(a) What was the time duration of the entire experiment (from the introduction of the mould until its disappearance)? [3 marks]

(b) Graph the radius of the disc against elapsed time since the start of the

experiment. [3 marks]

(c) How fast was the area of the disc increasing (cm2

/hour) just before the

antibiotic was introduced? [3 marks]

(d) What was the maximum area of the disc? [3 marks]

(e) How fast was the area of the disc decreasing (cm2

/hour) just as the disc

disappeared due to the antibiotic? [3 marks]