Keisha has a budget of $3,000 to set up an event for her company. She decided to guard against going over budget, she left 10% of the budget for a contingency fund. This leaves a budget of $3,000 - 10*3000/100 = $2,700.
Now analyze the possible vendors, considering it's expected to have 70 people attending the event (35 employees + 35 guests).
Vendor A has the following cost scheme:
Décor: $300
Food: $15 per person * 70 = $1,050
Beverage: $53 per person * 70 = $3,710
Entertainment: $516 per person * 70 = $36,120
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Vendor B has the following cost scheme:
Décor: $500
Food: $18 per person * 70 = $1,260
Beverage: $55 per person * 70 = $3,850
Entertainment: $1,000
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Vendor C has the following cost scheme:
Décor: $750
Food: $5,800
Beverage: $500
Entertainment: $1,500
Since all vendors are of the same quality, Keisha should pick the cheapest choice for each item, that is:
Decor (From vendor A): $300
Food (From vendor A): $1,050
Beverage (From vendor C): $500
Entertainment (From vendor B): $1,000
Total budget: $300+$1,050+$500+$1000=$2,850
This is a valid option. She goes over her safe budget, but she can use part of that funds.
If her boss is not pleased by her choice above, we could try to replace some of the options with a more expensive item such that the total budges is not exceeded.
I cannot find any other combination of items that does not exceed the $3,000 limit, thus the presented combination is the only one that fulfills the conditions.