School-Safe Puzzle Games

Math Brainteaser- Marbles and Rocks

math brain teaser marbles

Grandma gave Eli a box containing equal numbers of marbles and rocks. After Eli rolled 36 marbles away, there were 3 times as many rocks as marbles.  How many marbles were there to begin with?

This can be solved without any formal algebra training. Answers can be submitted below, will reveal before the week is over!

Want more of a challenge? Check out this very hard math brainteaser from the Smart-Kit Archive! Otherwise be sure to check out our fun & brainy Smart Games!

12 Comments to “Math Brainteaser- Marbles and Rocks”


  1. Falwan | Profile

    ++++++++++++++++++++++++++++++++++++++++++++++++


    54 MARBLES = 54 ROCKS


    ++++++++++++++++++++++++++++++++++++++++++++++++


  2. DoodleFish | Profile

    54 marbles


    starting with equal numbers of rocks and marbles, then have 3x as many rocks as marbles => 2/3 of the marbles were rolled away.


    36 x 1.5 =54


  3. engjs1960 | Profile

    36/2 = 18 + 36 = 54.


  4. Hendy | Profile

    54 marbles = 54 Rocks
    54 – 36 = 18
    18 * 3 = 54


  5. Shawn | PUZZLE GRANDMASTER | Profile

    But I like algebra!


    m=marbles
    r=rocks
    m=r


    When you take away 36 of the marbles, you are left with 1/3 of the original number of marbles.


    (m-36)*3=m


    m=54


  6. suineg | PUZZLE MASTER | Profile

    Ok, I think without algebra could be solved like this:
    Intially the proportion were 1::1 , when you substract 36 marbles the proportion goes 1::3
    so 2/3 =36 so 1/3 = 18 so initially you have 54 marbles… now that i think about it there was no equation right, so it must be valid for a non algebraic solution, cool.


  7. Hex | PUZZLE MASTER | Profile

    solve x=3(x-36)
    x=54 marbles


  8. BlindCupid | Profile

    48.


    36 / 3 = 12
    12 x 4 = 48


  9. prof | Profile

    36/2=18*3=54


  10. RogHyde | Profile

    Before: 54 marbles and 54 rocks
    After: 18 marbles and 54 rocks


Enter an Answer/Comment/Reply

To comment log in or register for a free Smartkit account.