Question

A marathon runner runs at a steady 15 km/hr. When the runner is 7.5 km from the finish, a bird begins flying from the runner to the finish at 30 km/hr. When the bird reaches the finish line, it turns around and flies back to the runner, and then turns around again, repeating the back-andforth trips until the runner reaches the finish line. How many kilometers does the bird travel?

Answer 1

Answer:

The value is $D = 15 \ km$

Explanation:

From the question we are told that

   The  speed of the marathon runner is  $v = 15 \ km /hr$

   The distance from the distance from the finish is  $d = 7.5 \ km$

   The  speed of the bird is  $v_b = 30 \ km / hr$

  Generally the time taken for the runner to reach the finish is mathematically represented as

       $t = \frac{d}{v}$

       $t = \frac{7.5}{15}$

        $t = \frac{1}{2}$

So the distance covered by the bird is  

      $D = v_b * t$

      $D = 30 * \frac{1}{2}$

         $D = 15 \ km$