Posted by Jake on Saturday, January 28, 2012 at 9:34pm.
How do I solve this if there is no equation to this
1. The population of the bacteria in a Petri dish increases by a factor of 10 every 10 hour. If there are initally 20 bacteria in the dish, how long will it take before the population increases to 60,000 to the nearest tenth of an hour?
a) 3000.0 h
b) 300.0 h
c) 4.8 h
d) 3.5 h
2. A certain radioactive isotope has a half life of 5 years. If a sample has 120 grams of radioactive material, what equation could be used to determine the amount of material remaining (y) after x years.
- Math - Reiny, Sunday, January 29, 2012 at 9:27am
doubling time is 10
amount = 20(10)^(x/10)
3000 = 10^(x/10)
log both sides
log 3000 = log 10^(x/10)
x/10 = log 3000
x = 10log3000 = 34.8 hrs.
at end of 10 hours; 20(10) = 200
at the end of 20 hrs = 200(10) = 2000
at the end of 30 hrs = 2000(10) = 20000
at the end of 40 hrs = 20000(10) = 200000
so the time must have been between 30 and 40 hours
amount = 20(10)^34.8/10)
none of your choices are correct.
amount = 120(1/2)^(x/5)
the way you typed your choices, none match my answer.
Answer This Question
More Related Questions
- calculus - a colony of bacteria living on a petri dish under optimal conditions ...
- Algebra 2 check my answer please? - The population of a bacteria in a Petri dish...
- Math - A culture of bacteria in a petri dish is doubling every hour. If there ...
- precal - A petri dish contains only two bacteria. The bacteria divide every half...
- math - Bacteria is growing in a petri dish. Initially, there were 15,000 ...
- precalculas - the amount of bacteria in a petri dish increased by a percent ...
- Algebra 1 - The initial number of bacteria in a Petri dish is 2,300 and grows at...
- pre algebra - there is 100 bacteria in a petri dish. every 30 minutes the ...
- math - A colony of bacteria is growing in a petri dish which has a maximum ...
- math - i have this question the population fucntion of bacteria is observed to ...