In a city 90% of the population own a car, 15% own a motor cycle, and everybody owns one or the other or both. Find the percentage of motorcycle owners to car owners.
In order to solve it i have first found out that 5% are the guys who owns owns one or the other or both. Now I require, Find the percentage of motorcycle owners to car owners.
I have added for car-ians : $90\,\% + 5\,\%=95\,\%$.
And motorcycl-ians: $15\,\% +5\,\%=20\,\%$.
Found out the ratio as $4:19$ but found it incorrect. why?
Good try, but you zigged when you should have zagged.
$90\%$ own a car, but some might also own a motorcycle. $15\%$ own a motorcycle, but some might also own a car.
It is correct that $5\%$ own both. But that means that $85\%$ own only a car, and $10\%$ own only a motorcycle. Those add up to $100\%$, as they should.
If you're looking for the ratio of motorcycle-only owners to car-only owners, it's $10/85 = 2/17.$
If you're looking for the ratio of motorcycle owners to car owners (regardless of whether or not they own both) it's $15/90 = 1/6$.