Answer:
9.6*10^-12
Explanation:
To calculate this, you will do the mass of 2 times 10^(-12) gram. So, 2*(10)^-12. Then we know 30 hours = 480,000,000 bacteria.
So now now you calculate the mass, 480,000,000 * 2(10)^-12 which gives you 9.6*10^-4.
Sorry if it sounds confusing! I hope this helps, have a good day! :D