A bag contains 10 red balls and 15 blue balls. Two balls are drawn randomly without replacement. Given that the first ball drawn is red, the probability (rounded off to 3 decimal places) that both balls drawn are red is \_\_\_\_.
The problem involves calculating the probability \( P(R_2 \mid R_1) \), where \( R_1 \) and \( R_2 \) represent the drawing of red balls in the first and second draws, respectively.
Step 1: Analyze the outcomes
Total number of balls: \( 25 \) (10 Red + 15 Blue).
Probability of drawing \( R_1 \) (a red ball in the first draw):
\[
P(R_1) = \frac{10}{25}.
\]
Step 2: Conditional probabilities
If \( R_1 \) is drawn, there are now \( 9 \) red balls and \( 15 \) blue balls left in the bag (total: \( 24 \)).
The probability of drawing \( R_2 \) (a red ball in the second draw given \( R_1 \)):
\[
P(R_2 \mid R_1) = \frac{9}{24}.
\]
Step 3: Final calculation
\[
P(R_2 \mid R_1) = 0.375.
\]
\section*{Final Answer}
\[
\boxed{0.375}
\]