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## Tamilnadu Samacheer Kalvi 9th Maths Chapter 8 Solutions Statistics Ex 8.1

Question 1.

In a week, temperature of a certain place is measured during winter are as follows 26°C, 24°C, 28°C, 31°C, 30°C, 26°C, 24°C. Find the mean temperature of the week.

Solution:

Mean temperature of the week = 27°C

Question 2.

The mean weight of 4 members of a family is 60kg. Three of them have the weight 56kg, 68kg and 72kg respectively. Find the weight of the fourth member.

Solution:

∴ The weight of the fourth member = 44 kg

Question 3.

In a class test in mathematics, 10 students scored 75 marks, 12 students scored 60 marks, 8 students scored 40 marks and 3 students scored 30 marks. Find the mean of their score.

Solution:

Total number of students = 10 + 12 + 8 + 3 = 33

Total score of 33 students = 10 × 75 + 12 × 60 + 8 × 40 + 3 × 30

= 750 + 720 + 320 + 90 = 1880

= 56.96 or 57 approximately

Question 4.

In a research laboratory scientists treated 6 mice with lung cancer using natural medicine. Ten days later, they measured the volume of the tumor in each mouse and given the results in the table.

Find the mean.

Solution:

x = 142.5 mm^{3}

Question 5.

If the mean of the following data is 20.2, then find the value of p

Solution:

(30 +p) 20.2 = 610+20p

606 +20.2p = 610+20p

20.2 p – 20p = 610 – 606 = 4

0.2 = 4

⇒

Question 6.

In the class, weight of students is measured for the class records. Calculate mean weight of the class students using Direct method.

Solution:

Question 7.

Calculate the mean of the following distribution using Assumed Mean Method:

Solution:

Let Assumed mean be 25

Question 8.

Find the Arithmetic Mean of the following data using Step Deviation Method

Solution:

Standard Deviation Method