The variables x x\,x and y y\,y are recorded and the results are shown in the table below
| xxx | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
| yyy | 429 | 754 | 871 | 1119 | 2478 | 2653 | 3050 | 3279 | 5470 | 7439 |
The data is coded using the changes of variable r=xr = xr=x and s=log10ys = \log_{10} ys=log10y
The product moment correlation coefficient for the coded data is 0.98 Comment on r r\,r for this model and therefore justify the use of a model in the form y=abxy = ab^xy=abx where a a\,a and b b\,b are constants
The regression line of r r\,r on s s\,s is found to be s=2.60+0.127rs = 2.60 + 0.127rs=2.60+0.127r
Find the values of a a\,a and bbb, give your answers to 3 significant figures
104 exam-style questions on OCR (MEI) A Level Maths 1.8 Exponentials and Logarithms, covering 1.8.1 The function y = a^x, 1.8.2 Convert between index and logarithmic form, 1.8.3 Logarithm as inverse of exponential, 1.8.4 Laws of logarithms, 1.8.5 Values of log_a a and log_a 1, 1.8.6 Solve equations of the form a^x = b, 1.8.7 Reduce y = ax^n and y = ab^x to linear form, 1.8.8 The function y = e^x, 1.8.9 Gradient of e^kx (A-level only), 1.8.10 The function y = ln x, and 1.8.11 Exponential growth and decay. Each one has a worked solution and a mark scheme showing where the marks go.