Question

in a class, 20 students are 1.15 metre tall, 15 student are 1.20 metre tall and five student are 1.25 metre tall. what is the average height of the student in the class ?​

Answer 1

Step-by-step explanation:

ANSWER

Given

x

=

5

∑x

i

=150

⇒

i=1

∑

5

x

i

=750....(i)

5

∑x

i

2

−(

x

)

2

=18

5

∑x

i

2

−(150)

2

=18

∑x

i

2

=112590.....(ii)

Given height of new student

x

6

=156

Now,

x

new

=

6

i=1

∑

6

x

i

=

6

750+156

=151

Also, New variance =

6

i=1

∑

6

x

i

2

−(

x

new

)

2

=

6

112590+(156)

2

−(151)

2

=22821−22801=20.

Answer 2

$\huge \sf { \fcolorbox{yellow}{g}{†Answer†}}$

Given

x= 5

∑x i

=150

⇒

i=1

∑ xi

=750....(i)

5∑x i2

−( x ) 2 =18

5

∑x 2

−(150) 2 =18

∑x =2