Ajar contains 150 coins. if it is very likely that you will randomly choose a penny out of the jar, how many pennies could be in the jar?

149 pennies.

Very likely: extremely likely, highly reasonable, almost certainly.

Considering the above definitions of "very likely", a jar of 150 coins, 149 of them being pennies, would satisfy each definition given for "very likely".

Almost certainly indicates that there is a possibility that you'd choose a coin that's not a penny, so a jar of 150 coins which are all pennies doesn't satisfy this definition.