The results using our method with observed FRB samples. Top panel: χ² described by Eq. (14) as a function of f_IGM × H₀ using the 30 FRB samples and our method. The black line indicates the χ² values derived by changing f_IGM × H₀. The blue line is the best-fit polynomial function to χ². Middle panel: PDF of f_IGM × H₀ from the χ² (top panel). The vertical dashed black lines correspond to the 84.2 and 15.8 percentiles (±σ) of the PDF. Bottom panel: PDF of H₀ by changing the scale from H₀ × f_IGM (middle panel) to H₀ for a given f_IGM = 0.85  ±  0.05. The solid vertical line indicates the peak of the PDF, and the dashed vertical lines indicate the uncertainty range of H₀ after taking the 0.05 error of f_IGM into account. The orange area indicates the CMB measurement of H₀ (e.g., Planck Collaboration VI 2020). The blue area shows the measurement by local distance ladders (e.g., Riess et al. 2022).