An inbred strain of plants has a mean height of 24 cm. A second strain of the same species also has a mean height of 24 cm. When these plants are crossed, the F1 are also 24 cm. However, when the F1 plants are crossed, the F2 plants show a wide range of heights; the majority of F2 are like P1 and F1, but approximately 4 of 1000 are only 12 cm tall and 4 of 1000 are 36 cm tall. What fraction of the F2 plants will be 27 cm in height