1968 AHSME Problems/Problem 4

Problem

Define an operation $\star$ for positive real numbers as $a\star b=\frac{ab}{a+b}$ . Then $4 \star (4 \star 4)$ equals:

$\text{(A) } \frac{3}{4}\quad \text{(B) } 1\quad \text{(C) } \frac{4}{3}\quad \text{(D) } 2\quad \text{(E )} \frac{16}{3}$

$4 \star 4 \star 4 = 4 \star 2 = \frac{4}{3}$

Therefore, our answer is $\fbox{C}$

Solution by VivekA

1968 AHSC (Problems • Answer Key • Resources)
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