Difference between revisions of "2018 AMC 10A Problems/Problem 3"

Revision as of 14:55, 8 February 2018

A unit of blood expires after $10!=10\cdot 9 \cdot 8 \cdots 1$ seconds. Yasin donates a unit of blood at noon of January 1. On what day does his unit of blood expire?

$\textbf{(A) }\text{January 2}\qquad\textbf{(B) }\text{January 12}\qquad\textbf{(C) }\text{January 22}\qquad\textbf{(D) }\text{Febuary 11}\qquad\textbf{(E) }\text{Febuary 12}$

Solution

$10! = 10\cdot 9\cdot 8\cdot 7\cdot 6\cdot 5\cdot 4\cdot 3\cdot 2\cdot 1$ Convert $10!$ seconds to minutes: $9\cdot 8\cdot 7\cdot 5\cdot 4\cdot 3\cdot 2$ minutes Convert minutes to hours: $9\cdot 8\cdot 7\cdot 2$ hours. Convert hours to days: $3\cdot 7\cdot 2 = 42$ days.

$42$ days after January 1 is $\fbox{\textbf{(E) }\text{Febuary 12}}$

2018 AMC 10A (Problems • Answer Key • Resources)
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 <math>42</math> days after January 1 is <math>\fbox{\textbf{(E) }\text{Febuary 12}}</math>
+== See Also ==
+{{AMC10 box|year=2018|ab=A|num-b=2|num-a=4}}
+{{MAA Notice}}

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Difference between revisions of "2018 AMC 10A Problems/Problem 3"

Revision as of 14:55, 8 February 2018

Solution

See Also