diff --git a/book/pd/exercises/exercise-paint.md b/book/pd/exercises/exercise-paint.md index f2c697b94b2e187b2e03b7c5bff5c81baab42665..490d72488782e45741eed5080fdab17a16df03c0 100644 --- a/book/pd/exercises/exercise-paint.md +++ b/book/pd/exercises/exercise-paint.md @@ -74,9 +74,9 @@ $$C_{paint} + C_{cleaning} + P_{f,1y} \cdot (C_{paint} + C_{cleaning} + C_{repai | Paint | Cleaning | Expected cost [€/yr] | |------- |--- | --- | | High-Quality | Stripping | 61.12 | -| High-Quality | Sanding | 61.0 | -| Low-Quality | Stripping | **45.4** | -| Low-Quality | Sanding | 83.0 | +| High-Quality | Sanding | 55.90 | +| Low-Quality | Stripping | **45.40** | +| Low-Quality | Sanding | 77.50 | Low Quality Paint + High Quality Cleaning ``` @@ -96,6 +96,8 @@ $$C_{paint} + C_{cleaning} + P_{f,10y} \cdot (C_{paint} + C_{cleaning} + C_{repa | Low-Quality | Sanding | 375.2 | High Quality Paint + High Quality Cleaning + +**NOTE:** If you're getting slightly different results, don't panic! Most likely you have approximated the probabilities computed above in question 2. ``` Assume the owner has decided to use the cheap paint system, and is simply going to sand it off (i.e. the cheap cleaning method) and re-apply the same system every year (i.e., for these problems consider a 1-year reference period). You have been asked to assess whether it is worthwhile to use a quick sonic test system to prevent failures during the year, and if it is, the number of tests that should be performed per year. Each test costs about €3 per m2, and if a weak spot is found, a new layer of paint can be easily applied, lowering the failure probability by a factor of 0.50.