Klaus was replacing the roof on his house. he used 420 nails to attach all the pieces. each pieces of wood needed 7 nails to hold it he used 40 pieces of wood. how many pieces were left?

Rachel is studying the population of a particular bird species in a national park. she observes every 10th bird of that species that she can find in the park. her conclusion is that the birds living in the park who belong to that species generally feed on insects. rachel's sample is . based on the sample she picked, rachel's generalization is