Question

What is the value of $\left(\left((2+1)^{-1}+1\right)^{-1}+1\right)^{-1}+1?$

$\dfrac{5}{8}$

$\dfrac{11}{7}$

$\dfrac{8}{5}$

$\dfrac{18}{11}$

$\dfrac{15}{8}$

Answer: B

Concepts:fraction order of operations

Difficulty rating: 560

Small Hint:

Work from the innermost reciprocal outward

Big Hint:

After each reciprocal step, simplify before adding the next $1$

Solution:

We can simplify this as follows. $\begin{aligned} &\left(\left((2+1)^{-1}+1\right)^{-1}+1\right)^{-1}+1 \\ &=\left(\left(\dfrac{1}{3}+1\right)^{-1}+1\right)^{-1}+1 \\ &=\left(\dfrac{3}{4}+1\right)^{-1}+1 \\ &=\dfrac{4}{7} + 1 \\ &=\dfrac{11}{7} \end{aligned}$

Thus, B is the correct answer.

2018 AMC 10A Problem 1

Answer: B

Difficulty rating: 560

Small Hint:

Big Hint:

Solution:

Problem 1 in Other Years