Question

In a town, the population of 2 groups in an year are 4500 and 7500. In the next 10 years, the population of the first group increased by 20% while the total population increased by 25%. Find the rate of increase in the 2nd group.

• A. 26
• B. 28
• C. 27
• D. 31

Answer 1

The correct option is B 28

Total initial population $4500+7500$

$=12000$

After 10 years :-

Total population = 1200 + 25% of 12000

$=12000+3000$

$=15000$

Total population of $=4500+20\%$ of 4500

community -A

$=4500+900$

$=5400$

Let the increase in population of

community - B be x %

Total population of = 7500 + x % of 7500

Community - B $=7500+\frac{x}{100}\times 7500$

$=7500+75x$

$\therefore$ According to question,

$15000=5400+7500+75x$

$15000=12900+75x$

$2100=75x$

$x=28$

$\therefore$ There is 28 % increase