Q.

The following distribution gives the state-wise teacher student ratio in higher secondary schools of India. What is the mode and mean of this data?


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a

Mode=31.7,Mean=28.2

b

Mode=33.6,Mean=25.3

c

Mode=35.7,Mean=26.3

d

Mode=30.6,Mean=29.2  

answer is D.

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Detailed Solution

It is given the state-wise teacher student ratio in higher secondary schools of India.
Question ImageWe convert the data in terms of the following expression.
xi=lower limit + upper limit2

Number of students

xi

Number of statefi

(xi)×fi=xifi

15 - 20

17.5

3

52.5

20 - 25

22.5

8

180

25 - 30

27.5

9

247.5

30 - 35

32.5

10

325

35 - 40

37.5

3

112.5

40 - 45

42.5

0

0

45 - 50

47.5

0

0

50 - 55

52.5

2

105

 

 

Σfi=35

Σfixi=1022.5

From the table, we get
Σfi=35 Σfixi=1022.5 We know that,
Mean=ΣxifiΣfi
Mean=1022.535
Mean=29.2 We also know that,
Mode =l+f-f12f-f1-f2×h
Where:
llower limit of the modal class
ffrequency of the modal class
f1frequency of the class preceding the modal class
f2frequency of the class succeeding the modal class
hclass width
From the given table, we get that the maximum frequency is 10 and the corresponding class is 30-35. Therefore, 30-35 is the modal class.
So, we have
l=30, h=5, f=10, f1=9 and f2=3 Putting the values in the formula, we get
Mode=30+10-920-9-3×5 Mode=30+18×5
Mode=30+58
Mode=30+0.625
Mode=32.625 Therefore, the mode of the given frequency distribution is 32.625 and the mean is 29.2.
Hence, the correct option is 4.
 
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