ANSWER
1/3
Step-by-step explanation
We know that 2/3 of all the students in the orchestra play stringed instruments and that of that fraction, 1/2 play violins. To find how many students in the orchestra play violins, we have to multiply the two fractions. In other words, we have to find what fraction is half of the two thrids who play stringed instruments,
We have a number 2 in the numerator of the first fraction and the same number is in the denominator of the second fraction, thus these two numbers are canceled, and we have,
Hence, 1/3 of the students in the orchestra play violins.