Correct Answer: 4:1
Explanation:
Let x km . be covered in y hrs. then, 1st speed = (x / y) km/hr.2nd speed = [(x/2) / 2y)] km/hr. = (x/4y) km/hr.∴ Ratio of speed = x/y : x/4y = 1 :1/4 = 4: 1