4-4.A broadcasting station has five major subsystems that must all be operational before a show can go on the air. If each subsystem has the same reliability, what reliability would be required to be 95% certain of broadcast success? 98% certain? 99% certain?
4-6.MagTech assembles tape players from four major components arranged as follows:
The components can be purchased from three different vendors, who have supplied the following reliability data:
- If MagTech has decided to use only one vendor to supply all four components, which vendor should be selected?
- b.Would your decision change if all the components were assembled in series?
4-8.Examine the systems given below. Which system is more reliable, a or b? c or d? Now calculate the reliability of each system. Were your perceptions correct?
If it costs $1000 for each 90% reliable component, $1500 for each 93% component, $2000 for each 95% reliable component, and $10,000 to replace a failed system, which system would you choose, a or b? c or d?
4-10.La Pied manufactures high-quality orthopedic shoes. Over the past five years, the general public has “found” La Pied products, and sales have skyrocketed. One unanticipated result has been a sharp increase in factory returns for repair, since local shoe repair shops do not have the materials or expertise to fix La Pied products. The popular walking sandal has been targeted for redesign. Currently, the leather pieces are glued together, then stitched. There is a 70% chance that the glue will last for the life of the sandal, and a 50% chance that the stitching will remain intact. Determine the sandal's reliability. How would the reliability of the sandal increase if the company adds two more rows of stitching?
4-12.Karen Perez runs an office supply store that also performs simple office services, such as copying. It is time to purchase a new high-speed copier and Karen has learned that machine uptime is a critical factor in selection. She has gathered the following data on reliability and maintainability for the three copiers she is considering. Given that all other factors are equal, which machine should Karen purchase?
4-14.Nadia Algar is the overworked IT resource person for her department. In the next round of computer purchases, she is determined to recommend a vendor who does a better job of documenting possible errors in the system and whose customer service line is more responsive to the needs of her colleagues. Nadia compiled the following data over an eight-week observation period. Assuming 40 hours per week, which computer vendor should Nadia pursue?
A-12.Compute the quality–productivity ratio (QPR) for the Burger Doodle restaurant in parts (a) and (b) in ProblemA-11. (
A-11.Burger Doodle is a fast-food restaurant that processes an average of 680 food orders each day. The average cost of each order is $6.15. Four percent of the orders are incorrect, and only 10% of the defective orders can be corrected with additional food items at an average cost of $1.75. The remaining defective orders have to be thrown out. A. Compute the average product cost. b.In order to reduce the number of wrong orders, Burger Doodle is going to invest in a computerized ordering and cash register system. The cost of the system will increase the average order cost by $0.05 and will reduce defective orders to 1%. What is the annual net cost effect of this quality-improvement initiative?)