CAIE FP2 2014 June — Question 9

Exam BoardCAIE
ModuleFP2 (Further Pure Mathematics 2)
Year2014
SessionJune
TopicChi-squared distribution

9 A random sample of 200 observations of the continuous random variable \(X\) was taken and the values are summarised in the following table.
Interval\(1 \leqslant x < 2\)\(2 \leqslant x < 3\)\(3 \leqslant x < 4\)\(4 \leqslant x < 5\)\(5 \leqslant x < 6\)\(6 \leqslant x < 7\)\(7 \leqslant x < 8\)
Observed frequency634532252276
It is required to test the goodness of fit of the distribution with probability density function \(f\) given by $$f ( x ) = \begin{cases} \frac { 1 } { x \ln 8 } & 1 \leqslant x < 8
0 & \text { otherwise } \end{cases}$$ The relevant expected frequencies, correct to 2 decimal places, are given in the following table.
Interval\(1 \leqslant x < 2\)\(2 \leqslant x < 3\)\(3 \leqslant x < 4\)\(4 \leqslant x < 5\)\(5 \leqslant x < 6\)\(6 \leqslant x < 7\)\(7 \leqslant x < 8\)
Expected frequency66.67\(p\)27.67\(q\)17.5414.8312.84
Show that \(p = 39.00\), correct to 2 decimal places, and find the value of \(q\). Carry out a goodness of fit test at the 5\% significance level.