Answer
a. 500,000 $\Omega$
b. 500,000 $\Omega$
Work Step by Step
a. Since the measurement 500,000 $\Omega$ has one significant digit (the least), then it is the least accurate.
b. Since the precision of the measurement 500,000 $\Omega$ is 100,000, then it is the least precise measurement. The other values have precisions of 1000 and 10,000.