Step 1 :To find the probability that all three marbles drawn will be blue, we need to calculate the probability of drawing a blue marble on each of the three draws, and then multiply those probabilities together.
Step 2 :Since there are 7 blue marbles out of a total of 14 marbles (3 red + 7 blue + 4 green), the probability of drawing a blue marble on the first draw is \( \frac{7}{14} \).
Step 3 :After one blue marble is drawn, there will be 6 blue marbles left out of a total of 13 marbles, so the probability of drawing a blue marble on the second draw is \( \frac{6}{13} \).
Step 4 :Finally, after two blue marbles are drawn, there will be 5 blue marbles left out of a total of 12 marbles, so the probability of drawing a blue marble on the third draw is \( \frac{5}{12} \).
Step 5 :Multiplying these probabilities together will give the final answer: \( \frac{7}{14} \times \frac{6}{13} \times \frac{5}{12} \).
Step 6 :The final probability is \( \frac{7}{14} \times \frac{6}{13} \times \frac{5}{12} = 0.09615384615384616 \).
Step 7 :Rounding to the nearest 10th of a percent, the final probability is 9.6%.
Step 8 :Final Answer: \( \boxed{9.6} \)