Final answer:
By dividing the 1,134 patients who stayed less than one day by the percentage of 0.21, we find that approximately 5,400 patients were treated in the hospital during January.
Step-by-step explanation:
If 21% of hospital patients stay for less than 1 day, and 1,134 patients stayed less than 1 day in January, we can find the total number of patients treated in January by dividing the number of patients who stayed less than one day by the percentage (in decimal form) that represents that group.
To find the total number of patients, we calculate: 1,134 ÷ 0.21 = 5,400 (rounded to the nearest whole number).
Therefore, the hospital treated approximately 5,400 patients in January.