Crossing The River In Minimum Time Puzzle
Four people need to cross a dark river at night. * They have only one torch and the river is too risky to cross without the torch. * If all people cross simultaneously then torch light wont be sufficient. * Speed of each person of crossing the river is different.cross time for each person is 1 min, 2 minutes, 7 minutes and 10 minutes. What is the shortest time needed for all four of them to cross the river ?



 according to me it must be 10 minutes , cause all 4 will cross it at the same time and it is not mentioned that they cannot cross it at the same time .....
if it is correct mark as brainliest plzzz..........