Case Study Based Question on Statistics
For a particular year, following in the distribution of ages (in years) of primary school teachers in a district :
| Age (in years) | 15-20 | 20-25 | 25-30 | 30-35 | 35-40 | 40-45 | 45-50 |
| No. of Teachers | 10 | 30 | 50 | 50 | 30 | 6 | 4 |
(a) Determine the class limits of the fourth class interval.
(b) Find the class marks of the class 45-50. Also determine the class size.
(c) Write the sum of lower limit of first class interval and upper limit of fifth class interval.
(d) How many primary school teachers are of age more than or equal to 35 years.
Doubt by Veer
Solution :
(a) Fourth Class Interval is 30-35
Lower class limit is 30
Upper Class limit is 35
(b) Class Marks & Class size of the class 45-50
Class Marks (xi)
= [LL+UL]/ 2
= [45+50]/2
= 95/2
= 47.5
Class Size (h)
= UL-LL
= 50-45
= 5
(c) Lower limit of first class interval (15–20)
= 15
Upper limit of fifth class interval (35–40)
= 40
Sum = 15+40
= 55
(d) No. of primary school teachers which are of age more than or equal to 35 years
= 30+6+4
= 40