In a test, the marks obtained by 100 students (out of 50) are given below:

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Solution

Q.
In a test, the marks obtained by 100 students (out of 50) are given below:

Marks Obtained 0 – 10 10 – 20 20 – 30 30 – 40 40 – 50

Number of Student 12 23 34 25 6

Find the mean marks of the students.

Ans.
(24)

Marks Obtained 0 – 10 10 – 20 20 – 30 30 – 40 40 – 50 TOTAL

Number of Student 12 23 34 25 6 100

$x$ 5 15 25 35 45

$u$ -2 -1 0 1 2

$f u$ -24 -23 0 25 12 -10

Here, $\sum f = 100$ and $\sum f u = - 10$ , $h = 10, a = 25$

$Mean, \bar{x} = a + (\frac{\sum f u}{\sum f} \times h) = 25 + (\frac{- 10}{100} \times 10) = 25 - 1 = 24$

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