What is the minimum number of minutes that it will take for all of the pets to safely be together in Qasala?

Question

A Grundo, a Gnorbu, a Gelert, and a Grarrl need to walk from Sakhmet to Qasala during a really bad heat wave. The heat is so bad, it's not possible to cross the open desert without some sort of shade. Fortunately, they have one umbrella. Unfortunately, however, only a maximum of two pets at a time can fit under the umbrella. The Grundo can cross the desert alone in 20 minutes. The Gnorbu can make the crossing alone in 16 minutes. The Grarrl can make the crossing alone in 8 minutes. And the Gelert can make the crossing in 4 minutes. Note that when two pets are making the crossing, they must do so at the pace of the slower pet!

What is the minimum number of minutes that it will take for all of the pets to safely be together in Qasala?

Answer 1

answer is 48 minutes

solution
First Grarrl and Gelert will go together.. it will take 8 minutes
Gelert will come back with the umbrella.. it will take 4 minutes
Now, Gnorbu and Grundo will go together.. it will take 20 minutes
Grarrl will bring the umbrella back... it will take 8 minutes.
Finally, Gelert and Grarrl will go together.. it will take 8 minutes..

So totally it will take 48 minutes ( 8 + 4 + 20 + 8 + 8)

Please go through the reply properly and u wil find it right.
now pls give me my ten points..

Answer 2

Umm... 28 minutes.

Ok, lets have another go.

20 + 4 + 16 + 4 + 8 = 52

Answer 3

96