In a chemistry course, the professor conducts an exam at the end of

Question

https://gmatclub.com/forum/download/file.php?id=86752 In a chemistry course, the professor conducts an exam at the end of every month and grades the students who pass the exam. The grades are calculated on the basis of the mean score of the class (μ) and the standard deviation of each student’s score (σ). The following formula is used and individual grades are rounded to the nearest integer in the range -3 to 3. Individual grade = (Individual score – μ) / σ If a student’s grade is 3, the student is awarded a special recognition certificate. The graph shows the grades of students in January, February, and March. The graph GRAPH_1_PLACEHOLDER the claim that the average score of the class was the highest in March. The graph GRAPH_2_PLACEHOLDER the claim that the number of students who passed the exam was the highest in January. GMAT-Club-Forum-k8egte27.png

arushi118 · Answer

Neither supports nor refutes -> for both the blanks as:
- First blank: We cannot conclude anything about the average score of a particular month as the grade depends on 3 things: individual score, average score and the standard deviation. So a higher grade can be a result of lower value of standard deviation too.

- Second blank: We are not told that what is the passing grade. So cannot conclude this either.

kdipayan · Answer

First answer: neither supports nor refutes

Understand, grades are given only to student who have passed - "...... and grades the students who pass the exam". 
Number of students graded seems highest in the month of Feb, so the answer for the second is probably -  refutes

arushi118 · Answer

Yes this makes sense. My bad. Thankyou.

Dereno · Answer

Question 1: The graph —————— the claim that the average score of the class was the highest in March.

The formula provided is :

individual grade * SD = (individual score - Average) .

Thus, Average = individual score - (individual grade * SD).

Since, we don’t know the individual scores of each student.

Neither supports nor refutes.

Question 2: The graph ————- the claim that the number of students who passed the exam was the highest in January.

Let’s visualise the graph in table format.

Grades   
  Jan  
  Feb  
   March  
 
   -3 
  2 
  3 
  4 
 
   -2 
  3 
  5 
  3 
 
   -1 
  4 
  6 
  4 
 
   0 
  8 
 10 
  9 
 
   1 
  7 
  9 
  5 
 
   2  
  6 
  7 
  6 
 
   3 
  2 
  3 
  2  
 
    Total  
   32  
   43  
   33

The question mentions the data for the number of students who have passed. By looking the table, we can clearly say that the number of students passed is LOWEST for January.

Hence,  Refutes .

In a chemistry course, the professor conducts an exam at the end of

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Grades	Jan	Feb	March
-3	2	3	4
-2	3	5	3
-1	4	6	4
0	8	10	9
1	7	9	5
2	6	7	6
3	2	3	2
Total	32	43	33

GMAT Graphs and Tables (G&T) Questions

In a chemistry course, the professor conducts an exam at the end of

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