The equation of an ellipse where the major axis 2a is greater than the minor 2b (x-h)²/a² + (y-k)²/b² =1. When 2b>2a , then the equation becomes (y-h)²/b² + (x-k)²/a² =1 In our example a = 4 and b = 9. Moreover h=0 and k=0 because the center is on the origin, so the equation becomes: y²/b² + x²/a² = y²/81 + x²/16 = 1
To get the answer we can use proportion. 30 ------------- 100% 12 --------------x crossmultiply now 30x=12*100% 30x=1200% /:30 (divide both sides by 30) x=40% - its the percentage of cars which finished the race. 100%-40%=60% - its the answer