NCERT Class 11 - Math

Parvin Sinclair, G.P. Dikshit

Chapter 15 Statistics - all with Video Answers

Educators

Section 2

Measures of Dispersion

02:59

Problem 1

Find the mean and variance for each of the data.
$$
6,7,10,12,13,4,8,12
$$

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04:01

Problem 2

Find the mean and variance for each of the data.
First $n$ natural numbers

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Numerade Educator

03:20

Problem 3

Find the mean and variance for each of the data.
First 10 multiples of 3

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Numerade Educator

04:18

Find the mean and variance for each of the data.
$$
\begin{array}{|l|l|l|r|l|r|r|r|}
\hline x_{i} & 6 & 10 & 14 & 18 & 24 & 28 & 30 \\
\hline f_{i} & 2 & 4 & 7 & 12 & 8 & 4 & 3 \\
\hline
\end{array}
$$

Uma K.

Numerade Educator

04:16

Problem 5

Find the mean and variance for each of the data.
$$
\begin{array}{|r|r|r|r|r|r|r|r|}
\hline x_{i} & 92 & 93 & 97 & 98 & 102 & 104 & 109 \\
\hline f_{i} & 3 & 2 & 3 & 2 & 6 & 3 & 3 \\
\hline
\end{array}
$$

Uma K.

Numerade Educator

04:48

Problem 6

Find the mean and standard deviation using short-cut method.
$$
\begin{array}{|l|r|r|r|r|r|r|r|r|r|}
\hline x_{i} & 60 & 61 & 62 & 63 & 64 & 65 & 66 & 67 & 68 \\
\hline f_{i} & 2 & 1 & 12 & 29 & 25 & 12 & 10 & 4 & 5 \\
\hline
\end{array}
$$

Uma K.

Numerade Educator

04:29

Problem 7

Find the mean and variance for the following frequency distributions.
$$
\begin{array}{|l|c|c|c|c|c|c|c|}
\hline \text { Classes } & 0-30 & 30-60 & 60-90 & 90-120 & 120-150 & 150-180 & 180-210 \\
\hline \text { Frequencies } & 2 & 3 & 5 & 10 & 3 & 5 & 2 \\
\hline
\end{array}
$$

Uma K.

Numerade Educator

04:22

Problem 8

Find the mean and variance for the following frequency distributions.
$$
\begin{array}{|l|c|c|c|c|c|}
\hline \text { Classes } & 0-10 & 10-20 & 20-30 & 30-40 & 40-50 \\
\hline \text { Frequencies } & 5 & 8 & 15 & 16 & 6 \\
\hline
\end{array}
$$

Uma K.

Numerade Educator

05:41

Problem 9

Find the mean, variance and standard deviation using short-cut method
$$
\begin{array}{|l|c|c|c|c|c|c|c|c|c|}
\hline \begin{array}{l}
\text { Height } \\
\text { in cms }
\end{array} & 70-75 & 75-80 & 80-85 & 85-90 & 90-95 & 95-100 & 100-105 & 105-110 & 110-115 \\
\hline \begin{array}{l}
\text { No. of } \\
\text { children }
\end{array} & 3 & 4 & 7 & 7 & 15 & 9 & 6 & 6 & 3 \\
\hline
\end{array}
$$

Uma K.

Numerade Educator

04:52

Problem 10

The diameters of circles (in $\mathrm{mm}$ ) drawn in a design are given below:
$$
\begin{array}{|l|c|c|c|c|c|}
\hline \text { Diameters } & 33-36 & 37-40 & 41-44 & 45-48 & 49-52 \\
\hline \text { No. of circles } & 15 & 17 & 21 & 22 & 25 \\
\hline
\end{array}
$$

Uma K.

Numerade Educator