Arare bacterial culture is being grown in a lab. as time passes, the cells multiply in a specific pattern. after 1 day, there is only 1 cell. after 2 days, there are 5 cells. after 3 days, there are 11 cells. after 4 days, there are 19 cells. how many cells will there be after seven days?

Okay so there is a pattern here, so that being said if the pattern continues...

After 1 day, there is only 1 cell. 
After 2 days, there are 5 cells. 
After 3 days, there are 11 cells. 
After 4 days, there are 19 cells. 

so that being said if the pattern continues...

After 5 days there would be 29 
After 6 days there would be 41 
After 7 days there would be 55 

So there is your answer, after 7 days there would be 55 cells.