Number of persons

According to the question,

By taking a scale of 1 unit = 20 thousands, a bar graph of the above-given data can be constructed as follows:

(a) We can clearly observe that,

The age groups in which the population is same are 30 – 44 and 45 – 59.

(b) We know that,

The senior citizens are the people that are either from the age group of 60 – 74 or from the age group of 75 and above.

Hence,

We can calculate the number of senior citizens as follows:

Total no. of senior citizen = 80,000 + 40,000

= 1,20,000