# exponential growth and decay questions

**Question description**

Few questions left on my exponential growth and decay questions precalc worksheet.

1. A pesticide kills 40% of the bugs in a house per hour. If 25 bugs remain after 5 hours, how many bugs were originally in the house?

so far i have (1-.4)^5

2. A chemical spill occurs near a lake. Biologists estimated the original fish population to be 9000. Five days after the spill, biologists estimated the fish population to be 2700. Find the death rate of the fish. I got 27.226% is that correct?

3. Just before first period started, Cindy Lou who told Billy some juicy gossipy about you know who concerning you know what. The rumor spread.

A. If 400 people did not know the rumor at the beginning of school, and only 10 people did not know the rumor at the end of school 7 hours later what was the rate the rumor spread? I got 69.381%

B. How many people did not know about the rumor at lunchtime after 3.5 hours?

THanks

## Tutor Answer

Brown University

1271 Tutors

California Institute of Technology

2131 Tutors

Carnegie Mellon University

982 Tutors

Columbia University

1256 Tutors

Dartmouth University

2113 Tutors

Emory University

2279 Tutors

Harvard University

599 Tutors

Massachusetts Institute of Technology

2319 Tutors

New York University

1645 Tutors

Notre Dam University

1911 Tutors

Oklahoma University

2122 Tutors

Pennsylvania State University

932 Tutors

Princeton University

1211 Tutors

Stanford University

983 Tutors

University of California

1282 Tutors

Oxford University

123 Tutors

Yale University

2325 Tutors