On a shelf in the larder there are identical pieces of Gruyere cheese. Three mice, one small, one medium size and one big, visit the larder regularly to eat the cheese
. The small mouse eats a piece in 15 min
.The medium-sized one takes 7min 30sec
. The big mouse, the greedy one, eats a piece in 5 min
Sadly, one day there is just one piece of cheese there, still identical to all the pieces before. The three mice rush all at once to eat the cheese. They all eat at their normal pace.
How long will the three mice need to eat this piece of Gruyere?