After leaving the cockroaches in their metabolic chamber for one hour the gases in the chamber was measured. The fraction of oxygen in the chamber was 0.18. What is the metabolic rate of the cockroaches in ml O2/hr? Assume room air is 21% O2 and chamber volume = 500ml).
a. 22.5
b. 0.135
c. 0.225
d. 13.5
