volumes of pipes

For the first one, remember that it's just a half pipe. So the area is actually only half of the area of the entire circle.

For the second one, what's your working?

i didnt have any someone said that they thought it was 4????
i dont understand how they got that though and i dont know how to get 6.9

What were your steps?

someone told me this

Okay well that's just nonsense. Ignoring what that person said, how do you actually think you might go about answering this question? To clarify what it's asking, the cylinder on the left is filled with water. That water is tipped into the bigger cylinder on the right. To what height does the water reach?

i believe the water reaches 5cm yes?

What? Clearly not since MyMaths is giving you the right answer. In order to work out the height of water in the big cylinder, you firstly need to work out the volume of water in the small cylinder.

the volume of the small cylinder is 753.98223686155037723103441198708 correct?

Yes, what's the next step?

im not too sure, work out the larger cylinder?