Answer:
19. 4^9=262144
20. 349524
Step-by-step explanation:
Each week, the number of new cases is equal to 4^n, for the 9th week, this is equal to 4^9=262144.
The number of total cases each week is a geometric series. The sum of the first n terms of a geometric series with common ratio r and first term a is
a(1-r^n)/(1-r). Using this, 4(1-4^9)/(1-4)=349524.
