The following table shows marks secured by 140 students in an examination- Marks Number of students- 0-10 20- 10-20 24- 20-30 40- 30-40 36- 40-50 20- -Calculate mean marks by the step deviation method-

[ nbsp; Class interval amp; Frequency (f_i) amp; Class mark (x_i) amp; u_i = (x_i 25)/10 amp; f_i u_i; 0 10 ...

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Standard X

Mathematics

Mode for Grouped Data

The following...

Question

The following table shows marks secured by 140 students in an examination:
$\begin{matrix} Marks & Number of students 0 - 10 & 20 10 - 20 & 24 20 - 30 & 40 30 - 40 & 36 40 - 50 & 20 \end{matrix}$
Calculate mean marks by the step deviation method.

20.4

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25.86

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26.92

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Solution

The correct option is C
25.86

$\begin{matrix} Class interval & Frequency (f_{i}) & Class mark (x_{i}) & u_{i} = \frac{(x_{i} - 25)}{10} & f_{i} u_{i} 0 - 10 & 20 & 5 & - 2 & - 40 10 - 20 & 24 & 15 & - 1 & - 24 20 - 30 & 40 & 25 (= a) & 0 & 0 30 - 40 & 36 & 35 & 1 & 36 40 - 50 & 20 & 45 & 2 & 40 T o t a l & \sum f_{i} = 140 & \sum f_{i} u_{i} = 12 \end{matrix} Mean = a + 10 \times \frac{\sum f_{i} u_{i}}{\sum f_{i}} = 25 + 10 \times \frac{12}{140} = 25.86$

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The following table shows marks secured by 140 students in an examination: MarksNumber of students0−102010−202420−304030−403640−5020 Calculate mean marks by the step deviation method.

The correct option is C 25.86 Class intervalFrequency(fi)Class mark (xi)ui=(xi−25)10fiui0−10205−2−4010−202415−1−2420−304025(=a)0030−40363513640−502045240Total∑fi=140∑fiui=12Mean=a+10×∑fiui∑fi=25+10×12140=25.86

The following table shows marks secured by 140 students in an examination:
$\begin{matrix} Marks & Number of students 0 - 10 & 20 10 - 20 & 24 20 - 30 & 40 30 - 40 & 36 40 - 50 & 20 \end{matrix}$
Calculate mean marks by the step deviation method.