In a digital learning centre, there are three types of online tests. The average score of a student in the first and second test is 82.6. The average score in the second and third test is 84.2. The average of the first and third test is 80.4. If the student scored 2.5 marks less in the third test than in the first, find the marks obtained in the second test.
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Correct answer: B
Explanation
Given:
Average of first and second = 82.6
Average of second and third = 84.2
Average of first and third = 80.4
Third test score = First test score − 2.5
Average = (Sum of observations) ÷ 2
Let first test = x
Third test = x − 2.5
(x + Second) ÷ 2 = 82.6
x + Second = 165.2
(Second + x − 2.5) ÷ 2 = 84.2
Second + x − 2.5 = 168.4
Second + x = 170.9
(x + x − 2.5) ÷ 2 = 80.4
2x − 2.5 = 160.8
2x = 163.3
x = 81.65
x + Second = 165.2
81.65 + Second = 165.2
Second = 83.55