Final answer:
To solve the problem, set up a direct variation equation using the given information and solve for the constant of variation. Then, use the constant to find how many computers can be assembled in 15 hours. Hence the correct answer is option A
Step-by-step explanation:
To solve this problem, we need to set up a direct variation equation that relates the number of hours needed to assemble computers to the number of computers. Let's call the number of computers x and the number of hours y. We know that the number of computers varies directly with the number of hours, so we can write the equation as y = kx, where k is the constant of variation.
We can find the value of k by using the given information. When 12 computers are assembled in 9 hours, we can substitute these values into the equation: 9 = k(12). Solving for k, we get k = 9/12 = 3/4.
Now that we have the value of k, we can use it to find how many computers can be assembled in 15 hours. Substituting the values into the equation, we get 15 = (3/4)x. Solving for x, we get x = (4/3)(15) = 20.
Therefore, 20 computers can be assembled in 15 hours.
Hence the correct answer is option A