Question

The population of Bhopal is 12, 00,000. But 25% of the population dies due to the gas tragedy. The population increases at 10% p.a. However every year 20% of the new born child dies due to post effect of gas leakage. What will be the population of Bhopal after 4 years?

Answer 1

What a horrible question. Who thinks up this stuff?

There is not enough information. We don't know how many babies are born. We cannot compute 20% of a value that cannot be known.

Answer 2

Starting population: 1200000 (I am not going to use commas. British system has lakhs which is hundred thousand and they put comma to denote 12 lakhs).
25% of the population dies due to the gas leakage incident.
The population that remains is: 75% or 0.75 * 1200000 = 900000.

Every year population increases by 10%. For this problem we may have to assume this 10% is purely due to new births alone. Otherwise there is not enough info to work the problem. 20% or one-fifth of new borns persish. So the population increases by 8% each year.

Use the same formula as the one used to compute compound interest.

So in 4 years the population will be: 900000(1 + .08)^4

PS: This assumes no adult dies in those 4 years! Because if the adults die and the population still increases by 10% then more percentage of babies will have to be born to compensate for the adults dying.

Overall this problem is a horrible one with missing info.

Answer 3

1. 12,22,440


2. 12,27,540


3. 12,24,440


4. 12,28,660
options

Answer 4

There are ways to create reasonable assumptions. First, recognize the insufficiency of the problem statement.

Just throwing out numbers...

12,000,000 people
Say 60% Adult
7,200,000 adults
Say 50% are women
3,600,000 adult women
Say 40% of those are child-bearing age
1,440,000 adult women of child-bearing age
Say 90% are able to function in a behavior that might cause pregnancy.
1,296,000 Eligible for pregnancy
Say 90% actually manage pregnancy.
1,166,400
Say 85% of pregnancies manage to reach full-term
991,440
Say 80% of babies live more than 6 months
793,152

793,152 / 12,000,000 = 0.066096 -- Okay, 6%ish.

Frankly, I'm a little astonished how close this is to ranga's 8%, assuming that ALL the growth is in birthing babies.

Horrible assumption or no. Assumptions MUST be clearly explained.