Final answer:
Joe's assistant would take 40 minutes to assemble a computer working alone.
Step-by-step explanation:
To find out how long it would take Joe's assistant to assemble a computer working alone, we can first determine the rate of work for each person. Joe can complete 1 computer in 1 hour, so his work rate is 1 computer per hour. When working with an assistant, they can complete 1 computer in 40 minutes, which is equivalent to 2/3 of an hour. To find the assistant's work rate, we can divide the work done (1 computer) by the time taken (2/3 hour). So, the assistant's work rate is 1.5 computers per hour.
Now, let's use the work rate and time concept to find how long it would take the assistant to assemble a computer working alone. We know that the assistant's work rate is 1.5 computers per hour. Let's assume it takes the assistant 't' hours to assemble a computer alone. Using the work rate formula, we have 1.5 computers per hour multiplied by 't' hours equals 1 computer. Solving for 't', we get:
1.5t = 1
t = 1/1.5
t = 2/3
Therefore, it would take Joe's assistant 2/3 hour, or 40 minutes, to assemble a computer working alone.