The average of marks in Mathematics for 5 students was found to be 50. Later, it was discovered that in the case of one student the marks 48 were misread as 84. The correct average is :
Options:
A . 40.8
B . 40.2
C . 48.2
D . 42.8
Answer: Option D Answer: (d)Total marks obtained by 5 students = 50 × 5 = 250. Now, in this total marks, 84 is included instead of 48. ∴ Correct total marks = 250 – 84 + 48 = 214∴ Correct average = $214/5$ = 42.8 Aliter : Using rule 26,The correct average will be = m +${\text"(a-b)"}/ \text"n"$. Here, n = 5, m = 50 a = 48, b = 84 Correct Average = m +${\text"(a-b)"}/ \text"n"n$ = 50 +${(48-8)}/5$= 50 - $36/5$= 50 – 7.2 = 42.8
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