Saturday, March 24, 2018

POTW #24 - Algebra Unit Test Practice

Be sure to check last week's solution. It will help you for Thursday's forthcoming Unit test. Further, this week's POTW is for Algebra practice as well! Good luck.

POTW #23 Solution:

POTW #24 Question:

12 comments:

  1. - oldest child: 1000 and 1/10 of what remains
    - second oldest: 2000 and a 1/10 of what remains
    - thrid oldest: 3000 and a 1/10 of what remains
    - rest was distrubuted and each child receives the same amount.
    - how many children were there?

    I'm guessing we have to solve this algebraicly because it's called "practice for algebra unit test"..... So, guess I'm going to have to do that first.

    Let...
    - x represent the original amount of money
    - y represent how much each child receives
    - meaning that y/x would be the number of children

    First child got y= 1000 + (x-1000)/10
    Second child got y= 2000+ (x-2000)/10
    Third child y- 3000 + (x-2000)/10
    and so on.

    We can use the first and second children to solve this question.
    x= 1000 + (x-1000)/10
    Multiply by each side by 10 to get rid of the "/10"
    10x= 10000 + y-1000
    Reverse to find y
    y= 10x - 9000

    Second child:
    Gets 2000 and 1/10 of the remainder after the first child receives their fair share fo the money. Remove 2000. Do the same as the first child.
    x= 2000 + 1/10 (y-x-2000)
    10x= 20000 + y - x - 2000
    y= 11x - 18000
    Put both into equation since they are equal (question said they received the same amount)
    10x-9000 = 11x - 18000
    If 10x= 9000 and 11x is 18000, then x must be 9000 since 11x-10x=x and 18000-9000=9000
    If I replace in the euqation again, i can find y.
    y= (10 x 9000) - 9000
    y = 90000 - 9000
    y = 81000

    Number of children is y/x
    = 81000/9000
    = 9.
    There were 9 children and each of them recieved $9000.
    :)

    ReplyDelete
    Replies
    1. Shouldn't it be x/y?
      I think you switched up your variables.

      Delete
  2. There were a total of nine children receiving $9000 each in the will.

    ReplyDelete
  3. Grade 8 POTW

    There was a total of $81,000 divided evenly among 9 children, with each child recieving a $9000 inheritance. I did my work on paper.

    ReplyDelete
  4. My tab got deleted earlier because of WiFi issues, so I'll start where I left off.
    Let x be the amount of money at the start, let y be the amount of money each child receives.

    Use the first and second children to answer the main question.
    X = 1000 + (X-1000)/10
    10x = 10000 + y-1000
    y= 10x - 9000

    Repeat the equation above but using 2000 instead of 1000.
    X = 2000 + 1/10 (Y-X-2000)
    10x= 20000 + Y-X-2000
    y= 11x - 18000

    Then compare the two simplified equations to find the amount of money received in total as both children received the same amount of money
    10X - 9000 = 11X - 18000
    After simplifying, 11x - 10x = x, and 18000-9000 = 9000. X is equal to 9000.
    Then I can substitute X in the equation.
    Y = (10 x 9000) - 9000
    Y = 90000 - 9000
    Y = 81000
    The number of children can be found by dividing 81000 by 9000 because each received $9000.
    81000/9000 = 9.
    9 children received money.

    ReplyDelete
  5. Grade 8 POTW:

    My work is done here:
    https://docs.google.com/document/d/1Q6eTTob9ozzsX21xtl0wAgE6EMXTuuAXu2U9diol4KA/edit

    There were a total of 9 children.

    ReplyDelete
  6. let x = the amount of money that each child recieves
    let y = the total amount of money

    First child:
    x = 1000 + 1/10(y-1000)
    x - 1000 = 1/10(y-1000)
    10x - 10000 = y - 1000
    10 x - 9000 = y
    y = 10x - 9000

    Now I know the value of y and I can substitute it in later to find the value of x.

    Second child:
    x = 2000 + 1/10(y-x-2000)
    10x = 20000 + y - x - 2000
    11x = 20000 + y - 2000
    11 x = 18000 + y
    11x - 18000 = y

    Now that the y is isolated, I can substitute it.
    y = 11x - 18000
    10x - 9000 = 11x - 18000
    10x + 9000 = 11x
    9000 = x
    This means that each child receives $9000.
    Now I know the value of x and I can plug it into the equation to find the value of y.

    y = 10x - 9000
    y = 10(9000) - 9000
    y = 90000- 9000
    y = 81000
    This means that there the father gave a total of $81000 to his kids.

    To find out how many kids there are, I have to divide the total amount of money by the amount of money that each kids receives.

    81000 / 9000 = 9

    There are a total of 9 children.

    (Check was done on paper)

    ReplyDelete
  7. Grade 7/8 POTW
    I did the question earlier, but I think it didn't send so I will briefly talk about it.
    I got 3 answers for this question. For the first one, the one considered right by the actual POTW answer in the next question, I got 9 using pretty much the same algebraic method as some of the other students and the answer itself. I don't want to talk about that descriptively since it was what literally everyone pretty much did.
    My next answers are 0 and 1. This is because technically, the question did say that he gave it to his children, but if he had no children, $0 to no child and that is kind of it. I'm not sure if this counts though.
    For 1, if there is 1 child, he might have $1000 and he gives $1000 and then 1/10 of $0. I don't know if that counts either.
    Anyways, there were 0 or 1 or 9 children.

    ReplyDelete
  8. Sorry for not being on top of the POTW.
    1000 for first child+1/10 of remaining
    2000 for second child+1/10 of remaining
    3000 for third child+1/10 of remaining.

    Let x = Amount of money child recieves
    Let y = Total amount of money

    First child:
    x=1000+(y-1000)/10
    10x=10000+y-1000
    y=10x-9000

    Second Child:
    x=2000+(y-x-2000)/10
    10x=20000+y-x-2000
    10x+x=20000+y-2000
    11x=18000+y
    y=11x-18000

    Since both equations now equal y, we can make them both equal each other
    10x-9000=11x-18000
    -9000+18000=11x-10x
    9000=x

    Now we plug 9000 into our first equation
    y= 10(9000)-9000
    y=90000-9000
    y=81000

    81000/9000=9
    So there were a total of 9 children.

    ReplyDelete
  9. Grade 7/8 POTW:

    - oldest child: $1000 + 1/10 of what remains
    - second eldest: $2000 + 1/10 of what remains
    - third eldest: $3000 + 1/10 of what remains

    Let x = amount of money each child receives
    Let y = the total amount of money

    First Child:
    x = 1000+(y-2000)/10
    Second Child:
    x = 2000+(y-x-2000)/10

    Let's figure out the first and second child's uh... okay, I don't know what to call it. But let's figure out what they received.

    First Child:
    10x = 10000+y-1000
    y = 10x-9000

    Second Child:
    10x = 20000+y-x-2000
    10x+x = 20000+y-2000
    11x+x=20000+y-2000
    y=11x-18000

    So, both equations equal y. As both equal the same thing (says so in the equation) we can put them both into the equation.

    10x-9000 = 11x-18000
    -9000+18000 = 11x-10x
    9000 = x

    If the answer is indeed 9000, we can use this to find y by plugging it into the first equation:
    y = 10(9000)-9000
    y = 90000-9000
    y = 81000

    Now we divide y by x.
    81000/9000 = 9

    There were 9 children in total.

    ReplyDelete
  10. POTW:
    Let y = total amount of money
    let x = amount of money each child gets

    expressions for amount of money each child gets:
    oldest child: 1000 + 1/10(y-1000)
    second oldest: 2000 + 1/10(y-x-2000)
    third oldest: 3000 + 1/10(y-2x-3000)

    Since each child gets the same amount of money, the expression for the oldest child should be equal to the expression for the second oldest child.

    In the end, I found out that there were 9 children in total. Each one got $9000.

    ReplyDelete
  11. I'm not sure if my previous answer sent, so I'll just send another one to be sure.

    There were 9 kids in total and each got $9000 out of the $81000.

    ReplyDelete