sm1510
At a restaurant, a group of friends ordered four main dishes and three side dishes at a total cost of $91. The prices of the seven items, in dollars, were all different integers, and every main dish cost more than every side dish. What was the price, in dollars, of the most expensive side dish?
(1) The most expensive main dish cost $16.
(2) The least expensive side dish cost $10.
Deconstructing the QuestionWe have 7 items: 4 Main dishes (\(M\)) and 3 Side dishes (\(S\)).
Total Cost = $91.
Constraints:
1. All prices are distinct integers.
2. \(min(M) > max(S)\) (Every main dish costs more than every side dish).
Let the sorted prices be: \(s_1 < s_2 < s_3 < m_1 < m_2 < m_3 < m_4\).
Target: Find \(s_3\) (the most expensive side dish).
***
Analyze Statement (1)"The most expensive main dish cost $16."
So \(m_4 = 16\).
To check sufficiency, let's see if the prices are forced or if multiple sets exist.
To maximize the sum of the Main dishes (and thus minimize the Side dishes), we choose the largest possible distinct integers:
\(M = \{16, 15, 14, 13\}\). Sum = 58.
Remaining sum for sides: \(91 - 58 = 33\).
Since \(min(M)=13\), the max side dish must be \(\le 12\).
The largest possible sum for 3 distinct sides \(\le 12\) is \(12 + 11 + 10 = 33\).
This matches perfectly! So one solution is:
Sides: \(\{10, 11, 12\}\). Mains: \(\{13, 14, 15, 16\}\). Here \(s_3 = 12\).
Can we change the prices?
If we lower any Main dish price, the sum of Mains decreases -> the required sum of Sides increases.
Example: Lower \(m_1\) to 12. New Main Sum = 57. Required Side Sum = 34.
But now \(min(M)\) is 12, so \(max(S)\) must be \(\le 11\).
The max sum for sides \(\le 11\) is \(11 + 10 + 9 = 30\).
This is far below the required 34.
Conclusion: It is impossible to form any other set. The solution is unique.
SUFFICIENT***
Analyze Statement (2)"The least expensive side dish cost $10."
So \(s_1 = 10\).
Since all 7 prices must be distinct integers, the
minimum possible sum for 7 distinct integers starting at 10 is:
\(10 + 11 + 12 + 13 + 14 + 15 + 16\).
Let's verify the sum:
\(Sum = 10 + 11 + 12 + 13 + 14 + 15 + 16 = 91\).
This sum is exactly the Total Cost given in the prompt ($91).
This means there is
zero room to increase any price. The prices are locked into this exact sequence of consecutive integers.
The set is unique: Sides \(\{10, 11, 12\}\) and Mains \(\{13, 14, 15, 16\}\).
\(s_3 = 12\).
SUFFICIENT***
ConclusionBoth statements alone are sufficient.
Answer: D