Review A-Level Edexcel Biology arithmetic means through short calculations from biological datasets, including amino acid mass and cardiac-cycle timing.
The effect of atropine and propranolol on heart rate was investigated.
One group of people, group 1, were given propranolol each day for four days followed by atropine for four days.
A second group of people, group 2, were given atropine each day for four days followed by propranolol for four days.
The graph shows the results of this investigation.
Mean heart rate/ beats
Calculate the mean length of the cardiac cycle for group 2 on day 4.
Answer seconds