A commuter finds that she waits an average of 12.9 seconds at each of three stoplights, with a standard deviation of 7.5 seconds. Find the mean and the standard deviation of the total amount of time she waits at all three lights. What, if anything, did you assume

Acompany manufactures three types of cabinets. it makes 110 cabinets each week. in the first week, the sum of the number of type-1 cabinets and twice the number of type-2 cabinets produced was 10 more than the number of type-3 cabinets produced. the next week, the number of type-1 cabinets produced was three times more than in the first week, no type-2 cabinets were produced, and the number of type-3 cabinets produced was the same as in the previous week.