logic/word problem: stacking oranges (how many, total?)

[Trey]

A grocery clerk sets up a display of oranges in the form of a triangle using 9 oranges at the base and 1 at the top.
How many oranges were used by the clerk to make the arrangement?

Only part of the display is shown

      O
     O O 
    O O O 
   O O O O 
  O O O O O

I know that there are at least 19 oranges from the display and information, I keep coming up with 25...but my
choices are a)45 b)54 c)36 d)63 Thanks

 

[stapel]

I keep coming up with 25...

Please reply showing that work. You started at one end (maybe the bottom), and counted off the rows' numbers (9, 8, 7, ..., 1), then added (9 + 8 + 7 + ... + 1), and... then what?

Please be complete. Thank you!

Eliz.

 

[Trey]

I started at the bottom and worked to the top...9 + 7? + 5?+ 3?+ 1 = 25 that was my logic.
Trey

 

[stapel]

9 + 7? + 5?+ 3?+ 1 = 25 that was my logic.

Your numbers don't match your picture, so how did you arrive at them? Is the picture misleading? Do you have additional information which has yet to be posted?

Please reply with clarification, including what the question-marks in your sum indicate. Thank you!

Eliz.

 

[camgrover]

Looking at the picture you can tell that the number of oranges in each row is one less than row on which it sits.
Now, you know that the bottom row is 9.
Thinkkk!