Question

Do part (a) of question 7

Answer 1

Answer:

Step-by-step explanation:

We know that , if m is the midpoint for a class and h is the class size,

Lower limit of class = m - h/2

Upper limit of class = m + h/2

In the given table, class size = 30 - 10 = 20

So class interval for midpoint 10 is (10 - 20/2) and (10 + 20/2) = 0 - 20.

     class interval for midpoint 30 is (30 - 20/2) and (30 + 20/2) = 20 - 40

So continuing in this manner you can find the class interval.

Now create a table with class interval and frequency as columns.

Answer 2

7(a)

Given :

• Initial Mean of 9 number = 50
• On adding a new number , New mean = 54

Let :

• Sum of 9 number = x
• New number = y

To find :

New number included (y)

Formula used :

• Mean = Sum of observation ÷ Number of observations

Solution :

✭ Initial mean = Sum of 9 number ÷ 9

☞ 50 = x ÷ 9

☞ x = 50×9

☞ x = 450

✭ New mean = (Sum of 9 Number + New number) ÷ (9+1)

☞ 54 = ( x+y ) ÷ 10

✭ Putting value of x in above equation, we get;

☞ 54 = ( 450 + y) ÷ 10

☞ 54×10 = 450 + y

☞ y = 540 - 450

☞ y = 90

ANSWER :

New number included (y) = 90