Difference between revisions of "1989 AJHSME Problems/Problem 9"

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(Solution 2)
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==Solution 2==
 
==Solution 2==
<math></math>\frac{30}{2+3} = \frac{30}{5} = 6,<math> and that is the base unit. Since there are 2 boys for every 5 people, </math>6\cdot2=12.<math> Applying this into a fraction gives </math>\frac{12}{30} = \frac{2}{5} = 40\% = \boxed{\text{C}}.$
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<cmath>\frac{30}{2+3} = \frac{30}{5} = 6,</cmath> and that is the base unit. Since there are 2 boys for every 5 people, <math>6\cdot2=12.</math> Applying this into a fraction gives <math>\frac{12}{30} = \frac{2}{5} = 40\% = \boxed{\text{C}}.</math>
  
 
==See Also==
 
==See Also==

Revision as of 12:29, 28 December 2021

Problem

There are $2$ boys for every $3$ girls in Ms. Johnson's math class. If there are $30$ students in her class, what percent of them are boys?

$\text{(A)}\ 12\% \qquad \text{(B)}\ 20\% \qquad \text{(C)}\ 40\% \qquad \text{(D)}\ 60\% \qquad \text{(E)}\ 66\frac{2}{3}\%$

Solution

Besides ensuring the situation is possible, the $30$ students information is irrelevant.

From the first statement, we can deduce that $2$ of every $2+3=5$ students are boys. Thus, $2/5=40\% \rightarrow \boxed{\text{C}}$ of the students are boys.

Solution 2

\[\frac{30}{2+3} = \frac{30}{5} = 6,\] and that is the base unit. Since there are 2 boys for every 5 people, $6\cdot2=12.$ Applying this into a fraction gives $\frac{12}{30} = \frac{2}{5} = 40\% = \boxed{\text{C}}.$

See Also

1989 AJHSME (ProblemsAnswer KeyResources)
Preceded by
Problem 8
Followed by
Problem 10
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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