Let's solve the problem step by step.
Step 1: Determine how many members play the violin.
We know that there are 168 members in the orchestra and that \( \frac{3}{8} \) of them play the violin.
\[ \text{Number of violinists} = \frac{3}{8} \times 168 \]
Calculating this:
\[ \text{Number of violinists} = \frac{3 \times 168}{8} = \frac{504}{8} = 63 \]
So, there are 63 violinists.
Step 2: Determine how much time each violinist spends practicing each week.
We know that each non-violin member practices 40 hours each week. First, we determine how many non-violin members there are.
\[ \text{Number of non-violin members} = 168 - 63 = 105 \]
Now we calculate the total time spent practicing by non-violin members:
\[ \text{Total time for non-violin members} = 105 \times 40 = 4200 \text{ hours} \]
Since violinists practice \( \frac{2}{5} \) of the amount of time that non-violin members practice:
\[ \text{Time each violinist practices} = \frac{2}{5} \times 40 = \frac{80}{5} = 16 \text{ hours} \]
So, each violinist practices 16 hours each week.
Step 3: Use the answers from steps 1 & 2 to determine the total time spent practicing by all violinists.
Now we multiply the number of violinists by the time each one practices:
\[ \text{Total time for all violinists} = 63 \times 16 \]
Calculating this:
\[ \text{Total time for all violinists} = 1008 \text{ hours} \]
Therefore, the total time spent practicing by all violinists is 1008 hours.