 
 <translate> Give the step-by-step reasoning process and then the final answer. Under standard growth conditions, the bacterial strain, E.coli, has a doubling time of 20 minutes.  If 1 single bacterial cell is used to start a culture grown under standard growth conditions, how many bacterial cells will there be after the culture is grown for 4 hours? <hau> Bayyana tsarin tunani mataki-mataki sannan kuma amsar karshe. A karkashin yanayin girma na al'ada, kwayar cutar E.coli, tana da lokacin ninkawa na minti 20. Idan an yi amfani da kwayar kwayar cuta guda daya don fara al'ada da aka girma a karkashin yanayin girma na al'ada, da yawa kwayoyin cuta za su kasance bayan al'ada ta girma har tsawon sa'o'i 4? 