Final answer:
To find the value of y when x is 8, you calculate y by using the proportionality constant (1/12) obtained when y is 6 and x is 72, resulting in y being equal to 2/3.
Step-by-step explanation:
If y varies as x, this means that y is directly proportional to x. The proportionality can be expressed as y = kx, where k is the constant of proportionality. When x is 72, y is given as 6, so we can find k by dividing y by x (6/72), which simplifies to k = 1/12. Using this constant, we can determine the value of y when x is 8 with the formula y = kx, or y = (1/12) × 8. This calculates to y = 2/3, so the correct answer is B. ⅓.