Final answer:
To find out how many students play musical instruments, divide the number of students who play sports by 10, the simplified ratio. For 40 students who play sports, 40/10 = 4 students play musical instruments.
Step-by-step explanation:
The question involves determining how many students play musical instruments based on the ratio of students who play musical instruments to those who play sports.
Given that the ratio is 3:30, this can be simplified to 1:10, meaning that for every 10 students who play sports, there is 1 student who plays a musical instrument.
If there are 40 students who play sports, you can divide this number by 10 to find the number of students who play musical instruments. So, 40 divided by 10 equals 4.
Therefore, there are 4 students who play musical instruments.