Question

If the mean of the following distribution is 2.6, then the value of y is
Variable (x):
1
2
3
4
5
Frequency
4
5
y
1
2
(a)3
(b)8
(c)13
(d)24

Answer 1

SOLUTION :  

The correct option is (b) : 8  

Given : Mean = 2.6  

From the table , Σf = 12 + y , Σfx = 28 + 3y

Mean = Σfx /Σf

2.6 = (28 + 3y) / (12 + y)  

2.6 (12 + y) = (28 + 3y)

31.2 + 2.6y = (28 + 3y)

2.6 y - 3y = 28 - 31.2  

-0.4y = - 3.2

y = 3.2/0.4  

y = 32/4 = 8

y = 8  

Hence, the value of y is 8 .

HOPE THIS ANSWER WILL HELP YOU……

Answer 2

Option (b)

Answer = 8

⚫ Explaination ⚫

$\frac{Mean = Sum \: of \: observation }{no. \: of \: obsrvation \: }$


$= > 2.6 = \frac{28 +3 y}{12 + y}$


$= > 2.6(12 + y) = 28 + 3y$


$= > 31.2 + 2.6y = (28 + 3y)$


$= > 2.6y - 3y = 28 - 31.2$


$= > 0.4y = 3.2$


$= > y = \frac{3.2}{0.4}$


$= > y = \frac{32}{4} = 8$


$= > y = 8$