Sampling and Experiments · Superchallenge problem

A list holds the numbers $1, 2, \ldots, 100$ in increasing order. Plan A is a systematic sample of 10: a random start $r$ from 1 to 10, then every 10th entry. Plan B is a simple random sample of 10 entries. Let $\bar{x}$ be the sample mean. Find $\dfrac{\mathrm{Var}(\bar{x}) \text{ under B}}{\mathrm{Var}(\bar{x}) \text{ under A}}$.