One-tenth of the cars in a car park are yellow. Another car arrives and now one-ninth of the cars are yellow.
How many cars are now in the car park?
Check your answer:-
x/10 number of cars are yellow initially.
as yellow car’s percent increases from 1/10th to 1/9th after new car arrives, so new car must be a yellow car.
So we can form this equation
1 + x/10 = (x+1)/9
Now we just need to solve this equation
on multiplying both sides by 9*10 =>
9*10 + 9x = 10x + 10
90 – 10 = 10x – 9x
x = 80
So there were 8 yellow cars initially among a total of 80 cars(i.e. 1/10th)
and a new yellow cars comes making 9 yellow cars in total of 81 cars.(i.e. 1/9th)
So answer to the question is 81. there are a total of 81 cars now.