F statistic comparing two bolt makers' variability

Twelve bolts from one maker have sample variance $0.0003$, and twelve from a rival have sample variance $0.0001$ (diameters in cm, assumed normal and independent). The question is whether the rival's diameters vary less. What is the value of the appropriate test statistic?

$F=3$. Comparing two normal variances uses the ratio of sample variances, larger over smaller: $0.0003/0.0001=3$, referred to an $F_{11,11}$ distribution.