YOU SAID:
I ran a marathon in less than three hours.
INTO JAPANESE
私は3時間以内にマラソンを走りました。
BACK INTO ENGLISH
I ran a marathon within three hours.
INTO JAPANESE
私は3時間以内にマラソンを走りました。
BACK INTO ENGLISH
I ran a marathon within three hours.
Come on, you can do better than that.