Student Marks Range Optimization
CAT 2022 Slot 2 · QA · Hard · Arithmetic
Five students, including Amit, appear for an examination in which possible marks are integers between 0 and 50, both inclusive. The average marks for all the students is 38 and exactly three students got more than 32. If no two students got the same marks and Amit got the least marks among the five students, then the difference between the highest and lowest possible marks of Amit is
- A.
21
- B.
24
- C.
20
- D.
22
C
Explanation
Let marks of 5 students in ascending order be . Total marks = . Exactly 3 students got , so , which means . And .
To find highest possible value of : To maximize , we should minimize and make close to . Min values for with distinct integers are 33, 34, 35. So . Since , , which exceeds 32 (contradiction). So can be at most 32. But . Wait, to maximize , we make ? No, to maximize , we MINIMIZE . Min : if , sum = 102. . Since , . So must sum to MORE to leave a smaller sum for . To get , sum of . To maximize , we set , then . To maximize , we minimize subject to . . With , . Wait, if , sum = 132 . If . Check if : sum = . All conditions met! So Max .
To minimize : Maximize . Max . Sum = . Then Min or check giving even smaller . Wait, , but if , sum = 190. Max .
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