For the heart rate :
n = number of heat beats = 36
t = time taken to measure = 30 s = 30/60 min = 0.5 min (since 1 min = 60 sec)
R = heart rate
Heart rate is given as
[tex]R = \frac{n }{t}[/tex]
inserting the values
[tex]R = \frac{36 }{0.5}[/tex]
R = 72 min⁻¹
For uncertainty :
Δn = uncertainty in number of heat beats = ± 2
Δt = uncertainty in time taken = ± 0.4 s = ± 0.4/60 min = ± 0.0067 min (since 1 min = 60 sec)
ΔR = uncertainty in heart rate
uncertainty in Heart rate is given as
[tex]\frac{\Delta R}{R}=\pm \left ( \frac{\Delta n}{n} + \frac{\Delta t}{t}\right )[/tex]
inserting the values
[tex]\frac{\Delta R}{72}=\pm \left ( \frac{2}{36} + \frac{0.0067}{0.5}\right )[/tex]
ΔR = ± 4.96 min⁻¹
