The "Luso" variety of wheat is resistant to the Hessian fly. In order to understand the genetic mechanism controlling this resistance, an agronomist plans to examine the progeny of a certain cross involving Luso and a nonresistant variety. Each progeny plant will be classified as resistant or susceptible and the agronomist will estimate the proportion of progeny that are resis-tant.13 How many progeny does he need to classify in order to guarantee that the standard error of his estimate of this proportion will not exceed 0.05?