 
<translate> Sa'o'i 4 daidai yake da 4 * 60 = minti 240. Idan lokacin ninkawa ya kai minti 20, to bayan minti 240, adadin kwayoyin zai ninka sau 240 / 20 = sau 12. Saboda haka, farawa da kwayar kwayar cuta guda daya, bayan sa'o'i 4, za a sami 1 * 2 * 2 * 2 * 2 * 2 * 2 * 2 * 2 * 2 * 2 * 2 * 2 = 4,096 kwayoyin cuta. Amsar ƙarshe: 4096. <eng> 4 hours is 4 * 60 = 240 minutes. If the doubling time is 20 minutes, then after 240 minutes, the number of bacteria would have doubled 240 / 20 = 12 times. Thus, starting with only 1 bacterial cell, after 4 hours, there will be 1 * 2 * 2 * 2 * 2 * 2 * 2 * 2 * 2 * 2 * 2 * 2 * 2 = 4,096 bacterial cells.
The final answer: 4096. 