Whenever a constraint has negative slack,the shadow price is zero.

Regardless of the degrees of freedom, every t-distribution is symmetric around zero.

Which of the following is not a correct statement about the systematic random sample?

A) This type of sample has the advantage of being usable even when we do not know the size of the frame and, thus, cannot label each elementary unit with a number.
B) This type of sample is a subset of a frame, or of an associated population, chosen by taking separate censuses in a randomly chosen subset of geographically distinct clusters into which the frame or population is naturally divided.
C) This type of sample is a subset of a frame, or of an associated population, chosen by randomly selecting one of the first k elements and then including every kth element hereafter until the desired sample size has been reached.
D) This type of sample might be used by a quality inspector who wants to determine the percentage of defective units produced on an assembly line that never shuts down.
E) Both "This type of sample is a subset of a frame, or of an associated population, chosen by taking separate censuses in a randomly chosen subset of geographically distinct clusters into which the frame or population is naturally divided" and "This type of sample is a subset of a frame, or of an associated population, chosen by randomly selecting one of the first k elements and then including every kth element hereafter until the desired sample size has been reached" are incorrect.

A rectangular playing field with a perimeter of $120$ meters is to have an area of at least $495$ square meters. Within what bounds must the length of the field lie?

A) between $30$ and $30+9\sqrt{5}$ meters
B) between $30-9\sqrt{5}$ and $30+9\sqrt{5}$ meters
C) between $28\frac{1}{2}$ and $30$ meters
D) between $28\frac{1}{2}$ and $30+9\sqrt{5}$ meters
E) between $28\frac{1}{2}$ and $9$ meters