Algebra 1
posted by Brittany
I am having trouble with a few questions....Wondering if you could help...My answers have the *** by them.....
1. A lab is growing bacteria in a culture dish. The amount of bacteria in the dish doubles every 3 hours. Initially, there are 500 bacteria in the dish. How many are in the dish after 9 hours?
A. 4,500 bacteria.
B. 4,000 bacteria.
C. 1,500 bacteria. ***
D. 13,500 bacteria.
2. Determine if the number is written in scientific notation. If not, explain 32 x 10^4.
A. No; it is not written as a power of 10.
B. No; the first factor is not a number between 1 and 10.***
C. Yes; the number is written in scientific notation.
3. Determine if the number is written in scientific notation. If not, explain 2.01 x 10^5.
A. No; it is not written as a power of 10.
B. No; the first factor is not a number between 1 and 10.***
C. Yes; the number is written in scientific notation.

Reiny
#1, they double ever 3 hours, so
after 3 hours you would have 1000
after 6 hours you would have 2000
after 9 hours you would have 4000
or: number = 500(2^(t/3)) , plug in t = 9
#2, correct
#3,
2.01 certainly IS a number between 1 and 10
so C 
Brittany
So is #1 wrong?

Brittany
Another question. An investment account earns 4% per year compounded annually. If the initial investment was $4,000.00, how much is in the account after 3 years? Round your answer to the nearest dollar.

Reiny
amount = 4000(1.04)^3
I get $ 4499.46 
Brittany
Thanks Reiny.
Respond to this Question
Similar Questions

Math
A culture of bacteria in a petri dish is doubling every hour. If there are 100 bacteria at time t=0, how many bacteria will there be in 12 hours? 
Algebra
It takes 30 days to fill a laboratory dish with bacteria. If the size of the bacteria doubles each day. How long did it take for the bacteria to fill one half of dish? 
algebra
It takes 30 days to fill a laboratory dish with bacteria. If the size of the bacteria doubles each day. How long did it take for the bacteria to fill one half of dish? 
Algebra
A lab is growing bacteria in a culture dish. The amount of bacteria in the dish doubles every 3 hours. Initially, there are 500 bacteria in the dish. How many are in the dish after 9 hours? 
math
A lab is growing bacteria in a culture dish. The amount of bacteria in the dish doubles every 3 hours. Initially, there are 500 bacteria in the dish. How many are in the dish after 9 hours? 
math
Bacteria is growing in a petri dish. Initially, there were 15,000 bacteria in the dish. It triples every 8 hours. Write the equation to represents this growth after t hours. 
pre algebra
there is 100 bacteria in a petri dish. every 30 minutes the bacteria doubles. how muchbacteria will there be in 3 hours. 
calculus
a colony of bacteria living on a petri dish under optimal conditions doubles in size every ten minutes. At noon on a certain day, the Petri dish completely covered with bacteria. At what times (to the nearest hour, minute and second) … 
Algebra
At noon, Professor Simon has a petri dish with 10,000 cells of Bacteria A. In another petri dish, he has 33,000 cells of Bacteria B. Every hour, Bacteria A grows by 8%. Every hour Bacteria B cells die off, decreasing the number of … 
Math NEED HELP URGENT
At noon, Professor Simon has a petri dish with 10,000 cells of Bacteria A. In another petri dish, he has 33,000 cells of Bacteria B. Every hour, Bacteria A grows by 8%. Every hour Bacteria B cells die off, decreasing the number of …