You are Here: Home >< Maths

# a level maths help watch

1. The population, P, of bacteria in an experiment can be modelled by the formula P = 100e0.4t,
where t is the time in hours after the experiment began.

How many whole hours after the experiment began does the population of bacteria first exceed 1 million, according to the model?
2. ok so you need to set up the equation. you know P = population and you want to know when the population > 1,000,000

therefore:

1,000,000 > 100e^0.4t

rearrange and take logs to find the value of t.
3. Do I need to know what e is?
4. (Original post by hollyeb3)
Do I need to know what e is?
e is most likely Euler's number. It's on your calculator
5. (Original post by have)
e is most likely Euler's number. It's on your calculator
lool how jarring. OP u dont need to know e because it gets removed after u find ln (ln= loge)
6. (Original post by hollyeb3)
Do I need to know what e is?
the "ln" button is the button for logarithm with base e, e being Euler's number which is irrational and transcendental (just like pi), equal to approx 2.71828.

Here's what you should know about e for A-level:
which means it will come up loads in questions relating to rate of change, because for , the rate of change is equal to the value.

and just for fun
7. (Original post by hollyeb3)
The population, P, of bacteria in an experiment can be modelled by the formula P = 100e0.4t,
where t is the time in hours after the experiment began.

How many whole hours after the experiment began does the population of bacteria first exceed 1 million, according to the model?
100e^0.4t > 1000000
I divide both sides by 100;
e^0.4t = 10000
now solve ?

### Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: June 20, 2018
The home of Results and Clearing

### 1,609

people online now

### 1,567,000

students helped last year
Today on TSR

Hang on, have Edexcel's come out already?

### University open days

1. Bournemouth University
Fri, 17 Aug '18
2. University of Bolton
Fri, 17 Aug '18
3. Bishop Grosseteste University
Fri, 17 Aug '18
Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams