The probability distribution of a discrete random variable X is defined as :

$P(X=x)=\left\{\begin{matrix}3kx & \text{for x =} & 1, 2, 3\\5k(x+2) & \text{for x =} & 4, 5\\0 & otherwise \end{matrix}\right.$

The mean of the distribution is :

$\frac{337}{83}$