Premise: A surfer with a yellow board rides a wave.

Hypothesis: A surfer is in a contest.
it is not possible to tell

Premise: A little girl in a red rain hat is playing in the mud with several adults.

Hypothesis: A little girl is playing.
yes

Premise: A boy wearing a helmet flips up his scooter as he skates between orange cones.

Hypothesis: A boy is not wearing a helmet while riding his scooter.
no

Premise: Two girls arm wrestle as another observes

Hypothesis: Three woman running around a track.
no