Answer: $70 is the expected cost.
Step-by-step explanation:
A toy with a defect is produced once every 4 hours on average. To calculate the total of toys with a defect at the end of a 40-hour work week, you must follow the next steps:
1. Divide the total of hours of the work week by the time average of a toy with a defect is produced in the factory:
This means 10 toys with a defect are produced on average in a 40-hour work week.
2. Now that you calculated the number of toys with a defect, multiply it by the cost to the factory to produce one defected toy which is 7$:

To conclude, $70 is the expected cost to the factory for toys with defects at the end of a 40-hour work week, having in mind that the factory produces a toy with a defect about once every 4 hours on average.