Normal Serum Potassium Level Fill-in-the-Blank

A laboratory technician is analyzing a patient's blood sample for electrolyte levels. The normal range for serum potassium (K⁺) is between 3.5 to 5.0 mEq/L. The technician reports that the patient's serum potassium level is ____ mEq/L.

Fill in the blank with the lower limit of the normal potassium range.