In an activity, students are pulling marbles from a large jar containing blue and red marbles. In their sample, students will calculate the proportion of red marbles. Which of the following sample sizes will have the smallest sampling variability?

Larger samples tend to give more stable estimates, so the proportion of red marbles varies less from sample to sample. Of the choices, 40 is the largest sample size, so it will have the smallest sampling variability.

AI-written and checked against the verified answer.