QUESTION: Premise: "People play on a big tree."
Hypothesis: "People are in a tree."
Do we know that the hypothesis entailed by the premise?

Let's solve it slowly: Playing on a tree is different from being in a tree.
The answer is it is not possible to tell.

QUESTION: Premise: "A smiling child with christmas colored clothing."
Hypothesis: "Someone is smiling."
Do we know that the hypothesis entailed by the premise?

Let's solve it slowly: A smiling child fits the category of someone performing the action of smiling.
The answer is yes.

QUESTION: Premise: "Lots of people at a place buying stuff from a food car."
Hypothesis: "A pizza delivery man is approaching the door carrying three pizzas for the college students."
Do we know that the hypothesis entailed by the premise?

Let's solve it slowly:
Have to be home for delivery and out to buy from a food car.
The answer is no.