1988 AHSME Problems/Problem 10

Problem

In an experiment, a scientific constant $C$ is determined to be $2.43865$ with an error of at most $\pm 0.00312$ . The experimenter wishes to announce a value for $C$ in which every digit is significant. That is, whatever $C$ is, the announced value must be the correct result when $C$ is rounded to that number of digits. The most accurate value the experimenter can announce for $C$ is

$\textbf{(A)}\ 2\qquad \textbf{(B)}\ 2.4\qquad \textbf{(C)}\ 2.43\qquad \textbf{(D)}\ 2.44\qquad \textbf{(E)}\ 2.439$

Solution

If added together, we have: $2.43865+0.00312=2.44177$ This rounds to $2.4$ If they subtracted, we have: $2.43865-0.00312=2.43553.$ This rounds to $2.4$ . Therefore, we have the answer to be $\fbox{\textbf{(D) 2.4}}$

1988 AHSME (Problems • Answer Key • Resources)
Preceded by Problem 9	Followed by Problem 11
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1988 AHSME Problems/Problem 10

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