Two boats are heading towards each other at constant speeds of 5 miles/hr and 21 miles/hr respectively. They begin at a distance 20 miles from each other. How far are they (in miles) one minute before they collide ? Choose the most appropriate option
A) 1 / 12
B) 5 / 12
C) 1 / 6
D) 13 / 30
E) 1 / 5

Rationale: the question asks : how far apart will they be 1 minute = 1 / 60 hours before they collide ? since the combined rate of the boats is 5 + 21 = 26 mph then 1 / 60 hours before they collide they ' ll be rate * time = distance - - > 26 * 1 / 60 = 13 / 30 miles apart . answer : d .
Answer: D