2024 AMC 8 Problems/Problem 12

Revision as of 02:10, 27 January 2024 by Niuniumaths (talk | contribs) (Video Solution 2 by SpreadTheMathLove)

Problem

Rohan keeps a total of 90 guppies in 4 fish tanks.

  • There is 1 more guppy in the 2nd tank than in the 1st tank.
  • There are 2 more guppies in the 3rd tank than in the 2nd tank.
  • There are 3 more guppies in the 4th tank than in the 3rd tank.

How many guppies are in the 4th tank?

$\textbf{(A)}\ 20 \qquad \textbf{(B)}\ 21 \qquad \textbf{(C)}\ 23 \qquad \textbf{(D)}\ 24 \qquad \textbf{(E)}\ 26$

Solution 1

Let $x$ denote the number of guppies in the first tank.

Then, we have the following for the number of guppies in the rest of the tanks:

  • $x + 1 =$ the number of guppies in the second tank
  • $x + 1 + 2 =$ the number of guppies in the third tank
  • $x + 1 + 2 + 3 =$ the number of guppies in the fourth tank

The number of guppies in all of the tanks combined is 90, so we can write the equation

$x + x + 1 + x + 1 + 2 + x + 1 + 2 + 3 = 90$.

Simplifying the equation gives

$4x + 10 = 90$.

Solving the resulting equation gives $x = 20$, so the number of guppies in the fourth tank is $20 + 1 + 2 + 3 = 26$.

Therefore, the correct answer is $\boxed{\textbf{(E)}\ 26}$.

- C. Ren, Thomas Grover Middle School ~andliu766 (Minor edits)

Video Solution 1 (easy to digest) by Power Solve

https://youtu.be/2UIVXOB4f0o?si=e1Q2EbdEfPB_Q5Ql&t=66

Video Solution 2 by SpreadTheMathLove

https://www.youtube.com/watch?v=RRTxlduaDs8

Video Solution by NiuniuMaths (Easy to understand!)

https://www.youtube.com/watch?v=V-xN8Njd_Lc

~NiuniuMaths

See Also

2024 AMC 8 (ProblemsAnswer KeyResources)
Preceded by
Problem 11
Followed by
Problem 13
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
All AJHSME/AMC 8 Problems and Solutions

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