## anonymous 4 years ago can someone help please?

1. TuringTest

better to just ask a question

2. anonymous

can someone help me im stumped on this problem i need help please. A computer is infected with the Sasser virus. Assume that it infects 20 other computers within 5 minutes; and that these PCs and servers each infect 20 more machines within another five minutes, etc. How long until 100 million computers are infected?

3. bahrom7893

the computer's screwed

4. bahrom7893

does it have something to do with powers turing? i suck at these types of questions

5. anonymous

logs and exponential functions

6. TuringTest

it's not my thing either...

7. anonymous

$20^{\frac{t}{5}}=100,000,000$

8. TuringTest

I almost came up with that!

9. anonymous

oh crap that is wrong. that will not do it

10. TuringTest

plus one in there right?

11. anonymous

because i was not counting the ones already infected

12. TuringTest

$20^{1+\frac t5}=10000000$

13. TuringTest

no?

14. anonymous

gotta sum this sucker up, let me see if i remember.

15. anonymous

10^8=20^5t

16. anonymous

should be $\frac{t}{5}$ or maybe what turing said, but we are neglecting the ones infected along the way

17. anonymous

$20+20^2+20^3+...$

18. anonymous

so lets try $\sum_{k=1}^n20^k=10^8$ $\frac{20^{n+1}-1}{19}=10^8$ $20^{n+1}=19\times 10^8$ $(n+1)=\frac{\ln(19\times 10^8)}{\ln(20)}$

19. anonymous

can you please explain what you have?

20. anonymous

i was summing the geomtric series $20 + 20^2+20^3+...$ and seeing when it would equal 10^8

21. anonymous

i get approximately 7, so that means around 35 minutes

22. anonymous

so it would 20^7 how can i log it

23. anonymous

I got it 20^5t=10^8

24. anonymous

20^0t=120/4

25. anonymous

t=30