having a hard time with some extra credit and review problem

having a hard time with some extra credit and review problems. hope you can help!

In a single-factor ANOVA problem involving 3 treatments, the sample means were 5,6, and If each observation in the third sample was increased by 20; the test statistic value f would Increase decrease remain the same increase by 20 decrease by 10

Solution

Increasing each observation by 20 would not affect the variances, because the spread of the data will be the same.

As the F statistic is about the variances ratio, then

OPTION C: Remain the same [ANSWER, C]