Two variables, x and y, are such that y = Axᵇ, where A and b are constants. When lny is plotted against lnx, a straight line graph is obtained which passes through the points (1.4, 5.8) and (2.2, 6.0).
- (i)Find the value of A and of b.[4]
- (ii)Calculate the value of y when x = 5.[2]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2015). The mark or mark type is shown in brackets.
- [M1] for attempt to find the gradient
- [A1] b = 0.25
- [M1] for a correct substitution of values from either point and attempt to obtain c or solution by simultaneous equations dealing with c = ln A
- [A1] leading to A = 233 or e^5.45
- [M1] for correct use of either equation in attempt to obtain y using their value of A and of b found in (i)
- [A1] leading to y = 348
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