You see a boat filled with people, yet there isn’t a single person on board. How is that possible?

You are given four results as below:
1111 = F
2222 = E
3333 = T
Then, can you find out how to code 4444?

Forwards I am heavy, backward I am not. What am I?

I am white when I am dirty, and black when I am clean. What am I?

In a school, there are four subjects. Seventy percent of students study English, seventy five percent of students study Science, eighty five percent of students study Mathematics and eighty percent of students study Spanish.

Can you calculate the percentage of students that study all four subjects?

I have a head like a cat and feet like a cat, but I am not a cat. What am I?

How many cubic feet of dirt are in a hole of one foot deep, three feet long, and two feet wide?

I am a type of vehicle that has two wheels and is powered by humans. What am I?
Hint 1: You can ride me for exercise.
Hint 2: I am environment-friendly.

Can you fill the blank with the correct number?

6 30 870 756030 _____

You need to complete the maze by entering from the entrance marked below in the figure near the yellow circle, bottom left and leaving from the exit point near the green circle, bottom middle.

Rule of Game: You can move only by exchanging green and yellow circles.