The amount of lead in a certain type of soil, when released by a standard extraction method, averages 86 parts per million (ppm). A new extraction method is tried on 40 specimens of the
soil, yielding a mean of 83 ppm lead and a standard deviation of 10 ppm.
(a) Is there significant evidence at the 5% level that the new method frees less lead from the
soil? What about the 1% level?
(b) A critic argues that because of variations in the soil, the effectiveness of the new method is
confounded with characteristics of the particular soil specimens used. Briefly describe a better
data production design that
avoids this criticism.

Write the expression in complete factored form. 5n_(c - 3) - n(c - 3) =

Write the contrapositive of the conditional statement. determine whether the contrapositive is true or false. if it is false, find a counterexample. a converse statement is formed by exchanging the hypothesis and conclusion of the conditional. a) a non-converse statement is not formed by exchanging the hypothesis and conclusion of the conditional. true b) a statement not formed by exchanging the hypothesis and conclusion of the conditional is a converse statement. false; an inverse statement is not formed by exchanging the hypothesis and conclusion of the conditional. c) a non-converse statement is formed by exchanging the hypothesis and conclusion of the conditional. false; an inverse statement is formed by negating both the hypothesis and conclusion of the conditional. d) a statement not formed by exchanging the hypothesis and conclusion of the conditional is not a converse statement. true

Which word in the sentence below is an interrogative pronoun? who is picking us up from school? whousisfrom