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1.6 Exponentials and logarithms

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Question 2

The population of a specific bacteria colony (NNN) recorded h h\,h hours after an experiment began is shown in the table below.

hhh12471012
NNN1902906602300790018000

The data is coded using the changes of variable x=hx = hx=h and y=log⁡10Ny = \log_{10} Ny=log10​N.

The regression line of y y\,y on x x\,x is found to be y=2.10+0.18xy = 2.10 + 0.18xy=2.10+0.18x.

a.

Given that the data can be modelled by an equation in the form N=abhN = ab^hN=abh where a a\,a and b b\,b are constants, find the values of a a\,a and b b\,b to 3 significant figures.

[3]
b.

Give an interpretation of the constant a a\,a in this equation.

[1]
c.

Explain why this model might not be reliable for predicting the population after 1 week.

[1]
Markscheme

1.6 Exponentials and logarithms Questions

  1. A Level
  2. /Maths
  3. /1.6 Exponentials and logarithms

104 exam-style questions on WJEC A Level Maths 1.6 Exponentials and logarithms, covering 1.6.1 Exponentials and logarithms, 1.6.2 Exponentials and logarithms, 1.6.3 Exponentials and logarithms, 1.6.4 Exponentials and logarithms, 1.6.5 Exponentials and logarithms, 1.6.6 Exponentials and logarithms, 1.6.7 Exponentials and logarithms, 1.6.8 Exponentials and logarithms, and 1.6.9 Exponentials and logarithms. Each one has a worked solution and a mark scheme showing where the marks go.

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