Solution

163559

Problem / game
Crossing the Bridge Back to problem
First name
Isaac, Mr Robinson and Miss Morgans
School
St. Joseph's RC Primary School, Newbury
Country
United Kingdom, UK
Age
0

FASTEST
Take the fastest two people and send them across;
Then send the fastest back across and give the lantern to the two slowest people.
They go across, then send the second fastest back across and together the two fastest go back across the bridge achieving the fastest time possible.

SLOWEST
Take the slowest two people and send them across;
Then send the slowest back across and give the lantern to the one of the fastest people, then they proceed across the bridge with the slowest, and the slowest gets sent back across for the other second fastest and they go back across together.
Achieving the slowest time possible.

We think that the best formulae in most situations would be the fastest one due to the way it functions.