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# Help! Maths exponential question! watch

1. A bacterial population N varies with time t (seconds) according to the general equation

Nt = N0e^-λt Where N0 and λ are constants.

i) Use your equation Nt= 83000e^-0.026t and plot a large graph with sufficient calculated values of N at suitable values of t so that you can read offthe decimal reduction time (values of t plotted may need to be higher than 100s depending on your value of λ).

ii) Calculate the decimal reduction time from the data in your equation.

iii) compare your answers in i) and ii) above.

2. (Original post by geek-mode)
A bacterial population N varies with time t (seconds) according to the general equation

Nt = N0e^-λt Where N0 and λ are constants.

i) Use your equation Nt= 83000e^-0.026t and plot a large graph with sufficient calculated values of N at suitable values of t so that you can read offthe decimal reduction time (values of t plotted may need to be higher than 100s depending on your value of λ).

ii) Calculate the decimal reduction time from the data in your equation.

iii) compare your answers in i) and ii) above.

Do you know what the graph of y=e^(-x) looks like? Do you know what the graphs of y= a f(x) and y=f(ax) look like relative to the graph of y=f(x)? That's all you need to be able to plot the graph they're asking for in the question - they're just after a sketch, not an accurate plot.

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Updated: April 2, 2013
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