Answer
d. SV = 30 mL; EF = 33%, HR = 85 bpm
Work Step by Step
Stroke volume is the amount of blood that gets pumped. It's what you started with minus what you have left after a heartbeat.
SV = EDV - ESV
SV = 90 mL - 60 mL
SV = 30 mL
Ejection fraction is the percent of blood that gets ejected. It's stroke volume divided by how much you started with.
EV = SV / EDV
EV = 30 mL / 90 mL
EV = 33.33%, rounded to 33%
Heart rate is how many times the heart beats per minute. Cardiac output is how much blood the heart pumps per minute. We also know how much blood is being ejected per pump. Putting these two together:
HR = CO / SV
HR = $\frac{2550 mL}{1 min}\times\frac{1 beat}{30 mL}$
HR = 85 bpm
