Once you've identified the root of your problems, talk to your academic advisor about what you need to do to boost your grades. Your advisor will be able to tell you what classes you need to repeat, or recommend classes that might interest you and help to bring up your GPA. Now that you have lined up your courses and are moving back to recovering from the failure, make a serious plan to help you stay on track and succeed the second time around. Make sure you give yourself enough time to study and complete assignments on a daily basis. It helps to figure out when you're most productive. Many people work best in the mornings. Choose a time during the day to get your most demanding tasks done and stick to a routine schedule. Take clear notes in class and during readings to make it easier to study for exams or organize papers later on. Study with a friend. Finding somebody to keep you motivated and on task can help with your academic performance. Enlist friends to quiz you on material, and don't be afraid to collaborate with peers whose work you respect. Universities are full of resources to ensure student success. The first step is being sure to attend all lectures, labs and tutorials available. Don't squander an opportunity to learn and grow! Join a study group. Studying with others helps keep you accountable, and makes learning a social and fun activity. Inquire into individual tutoring or assistance available on campus. One on one learning is a great way to go over tougher subject matter that might not get addressed during class time. While it's important to dedicate yourself to your studies, everybody needs time to relax and have fun. Picking up a personal calendar to keep track of your upcoming dates and deadlines is a great way to help you be efficient so that you can enjoy your spare time worry free. Find extracurriculars that interest you. Making time to engage in activities that you're passionate about will make it easier for you to de-stress and focus on work when necessary. Make time for important relationships. Don't force yourself to live in the library 24/7. Hang out with friends for a much needed break. College is also about growing socially, so it's important to let yourself meet new people and create meaningful relationships. This is easiest to do if you love what you're studying. Choose something you're passionate about and approach the material with a curious and creative mind. Don't try to simply memorize or cram for the test. Not only is this a poor method of information retention, but it makes the material seem mundane. Complete readings on time, talk to peers and professors about concepts that interest you, and take the initiative to research ways to become involved in internships or volunteer opportunities in fields you might want to pursue.

Summary: Meet with your academic advisor to figure out how to get back on track. Set up a new study plan. Take advantage of your resources. Manage your time and find a work-life balance. Learn to engage with the material.

The lead time is the time from when you decide to produce or order an item until the time at which the item is on hand and ready for sale to the end customer. There are several factors that can cause lead time to vary: Production delays If your own production process is variable, this may impact the lead time. In addition, the production process of the products you are ordering may vary. Material defects If you order 10 units and 2 are defective, you will have to wait for the additional 2 units. Delivery delays Shipping times can be expected to vary slightly at the best of times, and unexpected events like natural disasters or strikes can further delay delivery. To do so, you will need to adjust your standard deviation of demand to match the lead time period. Multiply your standard deviation of demand (calculated in Part I, step 4) by the square root of the lead time. This means if you calculated standard deviation on a monthly basis, and lead time was 2 months, you would multiply the standard deviation by the square root of two. Using our previous example, this means: 11 x 2 = 15.56. Make sure to convert lead time to the same unit of time measure that you used to determine standard deviation of demand. For example, if you calculated standard deviation on a monthly basis and lead time was 10 days, you would want to convert lead time to .329 months i.e. 10 divided by 30.42 (the average days in a month). We can combine formulas to determine safety stock based on demand with lead time factored in as follows: Safety stock = Z-score x lead time x standard deviation of demand In our example, to avoid stockouts 95% of the time, you would thus need 1.65 (the Z-score) x 2 (lead time) x 11 (standard deviation of demand) = 25.67 units of safety stock. If demand is constant but lead time variable, then you will need to calculate safety stock using the standard deviation of lead time. In this case, the formula will be: Safety stock = Z-score x standard deviation of lead time x average demand For example, if aiming for a Z-score of 1.65, with average demand constant at 20 units per month, and lead times over a six month period being 2, 1.5, 2.3, 1.9, 2.1, and 2.8 months, then Safety Stock = 1.65 x .43 x 20 = 14.3 units. If lead time and demand vary independently of one another (i.e. the factors leading to variance are different for each), then safety stock is the Z-score multiplied by the square root of the sum of the squares of demand and supply variability, or: Safety stock = Z-score x [(lead time x standard deviation of demand squared) + (standard deviation of lead time squared x average demand squared)] In our example: safety stock = 1.65 x [(2 x 11squared) + (.43 x 20)squared] = 29.3 units. That is, if the same factors impact lead time and demand variability, you will need to sum the individual safety stock calculations in order to assure yourself of adequate safety stock. In this case: Safety stock = (Z-score x lead time x standard deviation of demand) + (Z-score x standard deviation of lead time x average demand) In our example: safety stock = 25.67 + 14.3 = 39.97 units.
Summary: Factor in lead time to account for supply variability. Sync your stock with your supply delivery cycle. Put it all together. Calculate safety stock differently if lead time is the primary variable. Use a third equation to account for independent variation in both lead time and demand. Sum the calculations based on lead time and demand variability if the two factors vary dependently.