A girl reduced his speed to 5/8th and reaches her destination in 16 hours . If she had walked at her initial speed then how much time had she saved ?

6 hours

Ratio                            old     :      new

Speed                          8        :        5

Time                            5         :       8

According to question , 8R = 16 hours

                                  1R = 2 hours

    time saved if she walked by his usual speed is ,

                                 3R  =  6 hours