There are twenty students in a class, all of whom scored between 0 and

Question

There are twenty students in a class, all of whom scored between 0 and 100 on their final exams. If the class average was 85, how many people scored below the average score on the exam?

(1) Twelve people in the class scored higher than an 85.
(2) The lowest eight scores added up to 640.

nkin · Answer

IMO Option A

Stmt 1 is sufficient as it is straightforward.
Stmt 2: If 640 is total for 8 students, then their average is 80. This can be achieved with many combinations: All 8 students get 80, OR 6 get 80 and the other two get 74 and 86 and so on. Thus number of students above/below 85 will vary. Hence insufficient.

Hence option A

Anything I'm missing here?

wishalsp333 · Answer

There are twenty students in a class, all of whom scored between 0 and 100 on their final exams. If the class average was 85, how many people scored below the average score on the exam?

(1) Twelve people in the class scored higher than an 85.
(2) The lowest eight scores added up to 640.

1. 12 people have scored above average, but it doesn't tell the no of people who scored exactly 85. So A is insufficient.

2. 8 lowest scores added to 640, but there may be scores between 80 to 85 as well. So B is not sufficient.

Combining both 1 & 2 doesn't help. So C is insufficient.

So the option is E.

GaurSaini · Answer

Given that, Average of marks of 20 students is 85.
We need to find the number of students who received less than 85.

1. 12 students received more than 85, but no information is given on how many received equal to 85. Hence, insufficient.

2. 8 students received 85 on average, but no information is given on how many of them received more than 85 and less than 85.

Combining 1 & 2, We can't calculate number of students who received less than 85.

RS81 · Answer

There are twenty students in a class, all of whom scored between 0 and 100 on their final exams. If the class average was 85, how many people scored below the average score on the exam?

(1) Twelve people in the class scored higher than an 85.
(2) The lowest eight scores added up to 640.

Statement 1 = not enough as it does not talk about how many students scored 85
Statement 2 = Lower 8 average score is 80 (80*8=640). Good information but it again does not gives the information how many scored more than 85 or 85.
St 1 & St2 = combining both we get to know that 12 score more than 85 & 8 score average of 80.
But the problem remains same.  we dont know how many scored 85

bumpbot · Answer

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There are twenty students in a class, all of whom scored between 0 and

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