Question

The average life expectancy in three countries $A,B$ and $C$ was $75,90$ and $80$ years respectively. The ratio of population in the three countries wa $4:2:3$ respectively. What was the average life expectancy of the three countries combined?

• A. $75$
• B. $80$
• C. $81$
• D. $92$

Answer 1

Answer: (B)

$80$

given avergare life expectency are $75,90,80$ respectively

ratio of population $=4:2:3$

let the populations be $4x,2x,3x$

therefore the total population combined$=9x$

average life expectency $=\frac{75.4x+90.2x+80.3x}{9x}=80$

average life expectency combined is $80$