The concentration of a drug (C C\,C mg/L) in a patient's bloodstream t t\,t hours after administration is recorded in the table below.
| ttt | 1 | 2 | 4 | 6 | 8 | 10 |
| CCC | 26.3 | 19.1 | 10.0 | 5.2 | 2.8 | 1.4 |
The data is coded using the changes of variable x=tx = tx=t and y=log10Cy = \log_{10} Cy=log10C.
The regression line of y y\,y on x x\,x is found to be y=1.56−0.14xy = 1.56 - 0.14xy=1.56−0.14x.
Given that the data can be modelled by an equation in the form C=abtC = ab^tC=abt 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.
Give an interpretation of the constant a a\,a in this equation.
Explain why this model might not be reliable for calculating the concentration after 72 hours.
355 exam-style questions on OCR (MEI) A Level Maths 2.5 Statistical Hypothesis Testing, covering 2.5.1 Process and language of hypothesis testing, 2.5.2 When to apply 1-tail and 2-tail tests, 2.5.3 Significance level and incorrect rejection, 2.5.4 Null and alternative hypotheses (binomial), 2.5.5 Conduct a binomial hypothesis test, 2.5.6 Critical and acceptance regions (binomial), 2.5.7 Distribution of the sample mean (A-level only), 2.5.8 Hypothesis test for a single mean (A-level only), 2.5.9 Critical and acceptance regions (mean) (A-level only), 2.5.10 Correlation as closeness to a straight line (A-level only), 2.5.11 Inference using a correlation coefficient (A-level only), and 2.5 Statistical Hypothesis Testing. Each one has a worked solution and a mark scheme showing where the marks go.