Q3 of 55 Page 340

If the arithmetic mean of the data given below is 20.6, let us find the value of ‘a’

We have been given the arithmetic mean of the data, that is, 20.6.

⇒ Mean = 20.6


To find the value of a, we need to simply find mean using direct method.


So, let’s make a table showing frequencies and fixi.



So, we get


∑fixi = 530 + 25a


∑fi = 50


Using direct method, we have the formula of arithmetic mean as follows:



⇒ [∵ Mean = 20.6, ∑fixi = 530 + 25a & ∑fi = 50]


⇒ 1030 = 530 + 25a


⇒ 25a = 1030 – 530


⇒ 25a = 500


⇒


⇒ a = 20


Thus, a = 20.

More from this chapter

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1

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Let us find average age of my friends by direct method.

 2

I have written member of 50 families of our village in the table given below.


Let us write the average member of 50 families by the method of assumed mean.

 4

If the arithmetic mean of the distribution given below is 15, let us find the value of p.

 5

Rahamatchacha will go to retail market, for selling mangoes kept in 50 packing boxes. Let us write the number of boxes contained varing number of mangoes in the table given below.


Let us write the mean number of mangoes kept in 50 packing boxes. [using any method]