Answer 1

Total number of marbles = (6 + 4) = 10
Let S be the sample space.
Then n(S) = number of ways of selecting one marble out of 10 = ¹⁰C₁ = 10 ways 

Let E₁ = event of getting a white marble
∴ n(E₁) = ⁴C₁ = 4
Hence, required probability = \[\frac{^{4}{}{C}_1}{^{10}{}{C}_1} = \frac{4}{10} = \frac{2}{5}\]