(a) Four students of class XII are given a problem to solve independently. Their chances of solving the problem respectively are $\frac{1}{2}, \frac{1}{3}, \frac{2}{3}$ and $\frac{1}{5}$. Find the probability that at most one of them will solve the problem.\nOR\n(b) The probability distribution of a random variable X is given below :\n\begin{tabular}{|c|c|c|c|c|c|c|}\hline\text{X} & 1 & 2 & 4 & 2k & 3k & 5k \\\hline\text{P(X)} & $\frac{1}{2}$ & $\frac{1}{5}$ & $\frac{3}{25}$ & $\frac{1}{10}$ & $\frac{1}{25}$ & $\frac{1}{25}$ \\\hline\end{tabular}\nFind k, if $\text{E(X)} = 2 \cdot 94$ and also find $\text{P(X} \le 4)$.