# NCERT Solutions class-11 Maths Exercise 15.1

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Exercise 15.1

Find the mean deviation about the mean for the data in Exercises 1 and 2.

1. 4, 7, 8, 9, 10, 12, 13, 17

Ans. Mean of the given data

Mean deviation about mean = = = 3

2. 38, 70, 48, 40, 42, 55, 63, 46, 54, 44

Ans. Mean of the given data

= = 8.4

Find the mean deviation about the median for the data in Exercises 3 and 4.

3. 13, 17, 16, 14, 11, 13, 10, 16, 11, 18, 12, 17

Ans. Arranging the data in ascending order, 10, 11, 12, 13, 13, 14, 16, 11, 18, 12, 17

Here, (even number)

Mean =

= = 13.5

= = 2.33

4. 36, 72, 46, 42, 60, 45, 53, 46, 51, 49

Ans. Arranging the data in ascending order, 36, 42, 45, 46, 46, 49, 51, 53, 60, 72

Here, (even number)

Mean = = = 47.5

= = 7

Find the mean deviation about the mean for the data in Exercises 5 and 6.

5.

Ans.

Mean

= = 14

= = 6.32

6.

Ans.

Mean

= = 50

= = 16

Find the mean deviation about the median for the data in Exercises 7 and 8.

7.

Ans.

Here, = 13 and = 7

Median = 7

= = 3.23

8.

Ans.

Here, = 14.5 and = 21

Median = 30

= = 5.1

Find the mean deviation about the mean for the data in Exercises 9 and 10.

9.

Ans.

Mean

= = 358

= = 157.92

10.

Ans.

Mean

= = 125.3

= = 11.28

11. Find the mean deviation about median for the following data:

Ans.

Here, = 25

Median class = 20 – 30

Median =

= 20 + 7.86 = 27.86

= = 10.37

12. Calculate the mean deviation about median age for the age distribution of 100 persons given below:

Ans.

Here, = 50

Median class = 35.5 – 40.5

Median =

= 35.5 + 2.5 = 38

= = 7.35

### 6 thoughts on “NCERT Solutions class-11 Maths Exercise 15.1”

1. Bhut hi achi site ha smjh ma assani sa aagya

2. Error: for Q.5) mean deviation about mean=158/25=6.32 not 1258/25

3. Bilkul bekar sara short cut me likha hua hai puri shi se smja nhi rhe ho??

4. Thanks

5. Boht Achha a simple way se btaya hai

6. Samjane ka trika bda acha h bilkul hamare sir ki tarah ???