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Marks of a student were wrongly entered in computer as 83, actual marks of that student were 63. Due to this mistake average marks of whole class got increased by half (1/2). Find the total number of students in that class.

  • 25
  • 30
  • 35
  • 40
  • 45

Answer: Option D

Explanation:

Suppose total number of students are = X
\begin{aligned}
Total increase = x*\frac{1}{2} = \frac{x}{2} \\
=> \frac{x}{2} = 83-63 = 20 \\
=> x = 40
\end{aligned}

Similar Questions :

1. The average age of the mother and her six children is 12 years which is reduced by 5 years if the age of the mother is excluded. How old is the mother

  • 40
  • 41
  • 42
  • 43

Answer: Option C

2. Average of 10 matches is 32, How many runs one should should score to increase his average by 4 runs.

  • 70
  • 76
  • 78
  • 80

Answer: Option B

Explanation:

Average after 11 innings should be 36

So, Required score = (11 * 36) - (10 * 32)
= 396 - 320 = 76

3. Reeya obtained 65, 67, 76, 82 and 85 out of 100 in different subjects, What will be the average.

  • 70
  • 75
  • 80
  • 85

Answer: Option B

Explanation:

\begin{aligned}
( \frac {65+67+76+82+85}{5} ) = 75
\end{aligned}

4. If the average marks of three batches of 55, 60 and 45 students respectively is 50, 55, 60, then the average marks of all the students is

  • 54.48
  • 54.68
  • 54.60
  • 54.58

Answer: Option B

Explanation:

\begin{aligned}
\frac{(55 \times 50) +(60 \times 55) +(45 \times 60) }{55 + 60 + 45}
\end{aligned}

\begin{aligned}
\frac{8750}{160} = 54.68
\end{aligned}

5. Average age of boys in a class is 16 years and average age of girls is 15 years, what is the average age of all

  • 15.5
  • 15
  • 16
  • Cant be computed

Answer: Option D

Explanation:

As number of girls and boys is not given so result cant be computed

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