We are planning an experiment comparing three fertilizers. We will have

six experimental units per fertilizer and will do our test at the 5% level. One

of the fertilizers is the standard and the other two are new; the standard fertilizer

has an average yield of 10, and we would like to be able to detect the

situation when the new fertilizers have average yield 11 each. We expect the

error variance to be about 4. What sample size would we need if we want

power .9?