The difference between sex ratio and dependency ratio is given below:

Sex ratio Dependency ratio

The sex ratio, generally, denotes the number of males per 100 females.
The result which comes after dividing the population of 0-14 and 60 years and above by the population of 15-59 years age group and multiplied by 100 is called dependency ratio.

Sex ratio =Total number of males × 100 / Total number of females
Dependency ratio=Number of dependence × 100 / Active population

It is used to find out the ratio of male and female.
It is used to find out the ratio of active and dependent population.

Sex ratio increases due to preference to son. It increases due to increasing health status and facilities.
Difference between population size and population growth rate is given below:
Population size Population growth rate
Population size means the number of person s in population Population growth rate means the joint sum of natural growth rate of population and the net migration.
Population size is measured in number. Population growth rate is measured in percentage.
Here,
Midyear population (P) =4, 00,000
Birth (B) =25,000
Death (D) = 4,500
Immigration (I)=4000
Emigrants (E) =1098
According to the formula,
Net Migration rate(NMR) = ( (I-E) × 1000 ) / P
= ((4000-1098) × 1000) / 4,00,000
= (2092) / 400
= 7.25 Per thousand

Gross migration Rate(GMR) = ((I+E) × 1000 ) / P
= ((4000+1098) × 1000) / 4,00,000
= 5098 / 400
= 12.74
GMR =12.74 per thousand

Rate of Natural Increase:
= ((CBR-CDR) × 100) /1000
First of all let's calculate CBR & CDR
CBR = B × 1000 / P
= 25000 × 1000 / 4,00,000
=250 / 4
= 62.5

CDR= D × 100 / P
= 4500 × 1000 / 400000
= 45 / 4
= 11.25

CBR =62.5 per thousand CDR= 11.25 per thousand
Now,
We know that
RNI =((CBR-CDR) × 100) / 1000
=(62.5-11.25) × 100) / 1000
= -5.12 %
Rate of natural increase -5.12 %

Population Growth Rate
= (CBR-CDR+NMR) × 100 / 1000
= 58.5 / 10
= 5.85 %
Rate of population growth = 5.85 %

Population Doubling times
= 70 / Annual growth rate
=70 / 5.85
= 11.96
Population doubling time = 11.95 %

Given,
Crude Birth rate(CBR)= 20.5
Crude death rate(CDR)= 12.6
Net migration rate (NMR)= 8
Rate of natural increase (RNI)= ?
Population growth rate (PGR)= ?

We know,
RNI = (CBR-CDR)/1000*100
= (20.5-12.6)/1000*100
=. 79

Again PGR = (CBR-NMR)/1000 *100
=20.5-12.6+8/1000*100
=1.59%

Therefore, the RNI for the country's population is. 79% and PGR is 1.59% per annum.