In all, 52 children were assigned to the Montessori school and 114 to other schools at age three. When the children were five, parents of 38 of the Montessori children and 31 of the others could be located and agreed to and subsequently participated in testing. This information reveals a possible source of bias in the comparison of outcomes. Explain why. (Round your answers to the nearest whole number.) About % of Montessori parents participated in the study, compared to about % of the other parents.