Answer:
89 rooms should be set for early book customer
Step-by-step explanation:
According to the given data we have the following:
OVERAGE(CO) = 200
SHORTAGE(CS) = 500
In order to calculate how many rooms should be set for early book customer we would have to use the following formula:
OPTIMAL BOOKING = MEAN + (Z * STDEV)
MEAN = 75
STDEV = 25
SERVICE LEVEL= CS / (CS + CO) = 500 / (500 + 200) = 0.7143
Z VALUE FOR 0.7143 = 0.57
OPTIMAL BOOKING = 75 + (0.57 * 25) = 89
89 rooms should be set for early book customer
Line DQ is equal to 7. Since point Q is the centeriod, this means that line DQ will equal the same as line QD. Thus, line QD is 7 making like DQ 7 as well. Hope that helped :))
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Answer:

Step-by-step explanation:
Given,
Art electives = 3,
History electives = 4,
Computer electives = 5,
Total number of electives = 3 + 4 + 5 = 12,
Since, if a student chooses an art elective and a history elective,
So, the total combination of choosing an art elective and a history elective = 
Also, the total combination of choosing any 2 subjects out of 12 subjects = 
Hence, the probability that a student chooses an art elective and a history elective = 

Which is the required expression.