[填空题]
If the potassium isotor. )+8sdot euepq k75ej3rc; (vbzk6hpe $_{19}^{40}\text{K}$ gives $60\ \text{decays/s}$ in a liter of milk, estimate how much $_{19}^{40}\text{K}$ and regular $_{19}^{39}\text{K}$ are in a liter of milk. Use Appendix B.
$m_{40}$ = $mg$
$m_{39}$ = $mg$
