Difference between revisions of "2022 AMC 10A Problems/Problem 4"

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==Problem==
 
==Problem==
  
In some countries, automobile fuel efficiency is measured in liters per <math>100</math> kilometers while other countries use miles per gallon. Suppose that 1 kilometer equals <math>m</math> miles, and <math>1</math> gallon equals <math>l</math> liters. Which of the following gives the fuel efficiency in liters per <math>100</math> kilometers for a car that gets <math>x</math> miles per gallon`?
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In some countries, automobile fuel efficiency is measured in liters per <math>100</math> kilometers while other countries use miles per gallon. Suppose that 1 kilometer equals <math>m</math> miles, and <math>1</math> gallon equals <math>l</math> liters. Which of the following gives the fuel efficiency in liters per <math>100</math> kilometers for a car that gets <math>x</math> miles per gallon?
  
 
<math>\textbf{(A) } \frac{x}{100lm} \qquad \textbf{(B) } \frac{xlm}{100} \qquad \textbf{(C) } \frac{lm}{100x} \qquad \textbf{(D) } \frac{100}{xlm} \qquad \textbf{(E) } \frac{100lm}{x}</math>
 
<math>\textbf{(A) } \frac{x}{100lm} \qquad \textbf{(B) } \frac{xlm}{100} \qquad \textbf{(C) } \frac{lm}{100x} \qquad \textbf{(D) } \frac{100}{xlm} \qquad \textbf{(E) } \frac{100lm}{x}</math>

Revision as of 19:22, 11 November 2022

Problem

In some countries, automobile fuel efficiency is measured in liters per $100$ kilometers while other countries use miles per gallon. Suppose that 1 kilometer equals $m$ miles, and $1$ gallon equals $l$ liters. Which of the following gives the fuel efficiency in liters per $100$ kilometers for a car that gets $x$ miles per gallon?

$\textbf{(A) } \frac{x}{100lm} \qquad \textbf{(B) } \frac{xlm}{100} \qquad \textbf{(C) } \frac{lm}{100x} \qquad \textbf{(D) } \frac{100}{xlm} \qquad \textbf{(E) } \frac{100lm}{x}$

Solution

The formula for fuel efficiency is \[\frac{\text{Distance}}{\text{Gas Consumption}}.\] Note that $1$ mile equals $\frac 1m$ kilometers. We have \[\frac{x\text{ miles}}{1\text{ gallon}} = \frac{\frac{x}{m}\text{ kilometers}}{l\text{ liters}} = \frac{1\text{ kilometer}}{\frac{lm}{x}\text{ liters}} = \frac{100\text{ kilometers}}{\frac{100lm}{x}\text{ liters}}.\] Therefore, the answer is $\boxed{\textbf{(E) } \frac{100lm}{x}}.$

~MRENTHUSIASM

See Also

2022 AMC 10A (ProblemsAnswer KeyResources)
Preceded by
Problem 3
Followed by
Problem 5
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All AMC 10 Problems and Solutions

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