Mean Deviation

Q.

The standard deviation for the scores $1,2,3,4,5,6$ and $7$ is $2.$ Then, the standard deviation of $13,24,35,46,57,68$ and $79$ is

1. $2$

2. $4$

3. $22$

4. $11$

5. $44$

Q. Calculate the standard deviation of the following data.

$x$	$3$	$8$	$13$	$18$	$23$
$f$	$7$	$10$	$15$	$10$	$8$

Q. Find the median for the following frequency distribution.

$\begin{array}{cc}Ageinyears& Numberofpeople\\ 15& 3\\ 16& 8\\ 17& 10\\ 18& 10\\ 19& 5\\ 20& 4\end{array}$

1. 17

Q.

If $\mu$ is the mean of a distribution, then $\sum f_i(y_i-\mu )$ is equal to

1. mean deviation

2. standard deviation

3. 0

4. None of these

Q. Question 4
The weights of tea in 70 packets are shown in the following table
$\begin{array}{cc}\text{Weight(in~g) \& Number of packets}& \\ 200-201& 13\\ 201-202& 27\\ 202-203& 18\\ 203-204& 10\\ 204-205& 1\\ 205-206& 1\end{array}$
Find the mean weight of packets.

Q. If Mean deviation of a data is 16 find Quartile deviation __________.

1. 10.6
2. 12.3
3. 11.9
4. 13.35

Q.

100 surnames were randomly picked up from a local telephone directory and the frequency distribution of the number of letters in the English alphabets in the surnames was obtained as follows:

$\begin{array}{cc}Numberofletters& Numberofsurnames\\ 1-4& 6\\ 4-7& 30\\ 7-10& 40\\ 10-13& 16\\ 13-16& 4\\ 16-19& 4\end{array}$

Determine the median number of letters in the surnames. Find the mean number of letters in the surnames. Also, find the modal size of the surnames. [4 MARKS]

Q. Calculate the Mean and Standard Deviation for the following distribution:

Class-interval	Frequency
$0-4$	$2$
$5-9$	$3$
$10-14$	$10$
$15-19$	$3$
$20-24$	$2$

Q.

The mean deviation of the variates 40, 62, 68, 76, 54 from their arithmetic mean is

1. 9.4

2. 10

3. 11

4. 10.4

Q. Question 7
The weights (in kg) of 50 wrestlers are recorded in the following table.
$\begin{array}{cccccc}\text{Weight(in~kg)}& 100-110& 110-120& 120-130& 130-140& 140-150\\ \text{Number of wrestlers}& 4& 14& 21& 8& 3\end{array}$
Find the mean weight of the wrestlers.

Q. Find the mean deviation about the mean for the data in

$x_i$	$10$	$30$	$50$	$70$	$90$
$f_i$	$4$	$24$	$28$	$16$	$8$