The cache is not at the posted coordinates but is within 5km. To find the final, you will have to solve JAC's mathamatical problem below.
JAC has a jar of candy on his desk. The first day, JAC eats 1/3 of the candies in the jar. On the second day, JAC again eats 1/3 of the candies in the jar. On the third day, JAC eats another 1/3 of the candies in the jar. On the forth day, JAC counts how many candies are left in the jar and finds that there is 40 candies left. How many candies were in the jar on day 1?
Take the total number of candies and add it to the North coordinate and subtract it to the West coordinate to find the final cache location.