Difference between revisions of "2024 AMC 8 Problems/Problem 12"

Revision as of 17:26, 27 January 2024

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

How many guppies are in the 4th tank?

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

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:

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 ~andliu766 (Minor edits)

Suppose, there is no guppies in the first tank. The numbers of guppies in another tanks are $1,3,$ and $6,$ totally $10$ guppies.

We need to add $90 - 10 = 80$ guppies into $4$ tanks or $20$ guppies in each tank.

So the number of guppies in the fourth tank is $20 + 6 = \boxed{\textbf{(E)}\ 26}.$

vladimir.shelomovskii@gmail.com, vvsss

~NiuniuMaths

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 ~NiuniuMaths
+== Video Solution by CosineMethod [🔥Fast and Easy🔥]==
+https://www.youtube.com/watch?v=u5sC6tftndU
 ==See Also==
 {{AMC8 box|year=2024|num-b=11|num-a=13}}
 {{MAA Notice}}

2024 AMC 8 (Problems • Answer Key • Resources)
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