Can you find a number that lies one third of the distance between 1/3 and 2/3?

At my favorite fruit stand,
an orange costs 18,
a pineapple costs 27,
and a grape costs 15.
Using the same logic, can you tell how much a mango costs?

I am a type of room you cannot enter or leave. Raised from the ground below, I could be poisonous or a delicious treat. What am I?

What has many keys but can’t open a single lock?

Can you count the number of triangles inside a triangle?

What can you deduce from the following BrainBat?

CRY
LMKI

When does a USA Potato change its nationality?

I am a type of word that is spelt incorrectly or used differently, on purpose for humour. What am I?
Hint 1: You can find me in a joke.
Hint 2: I am a play on words.

John is the son of Jacob.
So,
Jacob is the_____of John's father?

Find the number of squares in the below-given picture.