shahparth1984 wrote:
The source is GMAT Free.
In the prompt, we have that 20% more people smoke than 20 years ago. Also, the first sentence says that the rate is higher than ever before. Combining them, say the population 20 years ago was 100, and x% of them smoked, which is 100x people. Today, the number of people that smoke is 1.2(100x). But the rate of smoking now is x or greater ("higher than ever before"), meaning that 1.2(100x) divided by the current population is greater than or equal to x:
[1.2(100x)][/P] >= x
Multiplying both sides by P and dividing both sides by x, we have:
1.2(100) >= P
Hi,
I did not read the word RATE in the main Q..
and if rate is given then I would answer the following way..
If RATE is given then we have some numeric value to work on and not merely %s...the remaining choices apart from C are all talking of numbers of smokers in the population or are talking of 13%, which does not have a basis anywhere..
So we have that number of smokers per 100/1000 person has increased..
and overall % has increased by 20%..
In normal scenario, an increase in % need not say anything about increase in number of smokers or decrease in the number..
say the population could have fallen down by more than 25% and the number of smokers has also fallen down slightly, this will give us an increased % in the number of smokers..
Here however we are given the rate..
so let the rate be x per 1000...
if P was the population then, the number of smokers= Px/1000..today the rate is higher than x, say the least x+ .0001..
If Pn is the population now, the number of smokers=(x+.0001)Pn/1000...now it is given that the % is increased by 20%..so (x+.0001)Pn/1000=1.2*Px/1000..
so Pn=1.2*P*x/(x+.0001)..
now x/(x+.0001) will always be less than 1 and depending on the increase in rate, it will depend how less it is from 1..so Pn=1.2*P*some value less than 1..
so C is correct..