The random variable $$\(X\)$$ has probability generating function $$\(\mathrm{G}_{X}(t)\)$$ given by $$\[ \mathrm{G}_{X}(t)=\frac{1}{5}+p t+q t^{2}, \]$$ where $$\(p\)$$ and $$\(q\)$$ are constants. Given that $$\(\mathrm{E}(X)=1.1\)$$, find the numerical value of $$\(\operatorname{Var}(X)\)$$. ........................................................................................................................................................ . ........................................................................................................................................................ . ........................................................................................................................................................ . ........................................................................................................................................................ . ........................................................................................................................................................ . ........................................................................................................................................................ . ........................................................................................................................................................ . ........................................................................................................................................................ . ........................................................................................................................................................ . ........................................................................................................................................................ . ........................................................................................................................................................ . ........................................................................................................................................................ . ........................................................................................................................................................ . ........................................................................................................................................................ . ........................................................................................................................................................ . ........................................................................................................................................................ . ........................................................................................................................................................ . ........................................................................................................................................................ . ........................................................................................................................................................ . ........................................................................................................................................................ . ........................................................................................................................................................ . ........................................................................................................................................................ . ........................................................................................................................................................ . ........................................................................................................................................................ . The random variable $$\(Y\)$$ has probability generating function $$\(\mathrm{G}_{Y}(t)\)$$ given by $$\[ \mathrm{G}_{Y}(t)=\frac{2}{3} t\left(1+\frac{1}{2} t^{2}\right) . \]$$ The random variable $$\(Z\)$$ is the sum of independent observations of $$\(X\)$$ and $$\(Y\)$$.

Further Mathematics
IGCSE&ALevel
CAIE
Exam No:9231_w24_qp_42 Year:2024 Question No:2(a)

Answer:



Knowledge points:

4.5.1.1 Including the discrete uniform, binomial, geometric and Poisson distributions.
4.5.2 use formulae for the mean and variance of a discrete random variable in terms of its PGF, and use these formulae to calculate the mean and variance of a given probability distribution

Solution:

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