Page 4 - Lesson note -1 -Ch.14 Statistics( Introduction,Presentation of Data)

8 - 6, 9 - 0, 8 - 4, 9 - 3, 7 - 8, 8 - 11, 8 - 7, 9 - 2, 7 - 10, 8 – 8
(i) What is the lowest age?
(ii) What is the highest age?
(iii) Determine the range?
Solution:
The ages of ten students of a group are:
8 - 6, 9 - 0, 8 - 4, 9 - 3, 7 - 8, 8 - 11, 8 - 7, 9 - 2, 7 - 10, 8 - 8.
(i) Lowest age = 7 years 8 months
(ii) Highest age = 9 years 3 months
(iii) Range = Highest age - Lowest age
= (9 years 3 months) – (7 years 8 months)
= 1 year 7 months

Question 5 : The monthly pocket money of six friends are given below:
Rs 45, Rs 30, Rs 40, Rs 50, Rs 25, Rs 45.
(i) What is the highest pocket money?
(ii) What is the lowest pocket money?
(iii) What is the range?
(iv) Arrange the amounts of pocket money in ascending order.
Solution:
The monthly pocket money of six friends are given below:
Rs 45, Rs 30, Rs 40, Rs 50, Rs 25, Rs 45
(i) Highest pocket money = Rs 50
(ii) Lowest pocket money = Rs 25
(iii) Range = Highest pocket money - Lowest pocket money
= Rs 50 – Rs 25= Rs 25
(iv) Ascending order is: Rs 25, Rs 30, Rs 40, Rs 45, Rs 45, Rs 50.

Question 6: Write the class -size in each of the following:
(i) 0-4, 5-9, 10-14
(ii) 100-120, 120-140, 160-180

Solution:
(i) 0-4, 5-9, 10-14
Since, classes are inclusive, so True lower limit of class = Lower limit of class - 0.5
and, True upper limit of class = Upper limit of class + 0.5
True class limits are 0.5-4.5, 4.5-9.5, 9.5-14.5
Therefore class size = 14.5 - 9.5 = 5
(ii) 100-120, 120-140, 160-180
Here the class limits and true class limits are the same
So, class size = 120 – 100 = 20