PRACTICE ANOTHER The administration of a large university wants to take a random sample to measure student opinion of a new food service on campus. It plans to use a scale from 1 to 100, on which 1 is complete dissatisfaction and 100 is complete satisfaction. The administration knows from past experience with such questions that the standard deviation for the responses is going to be about 3, but it does not know what to expect for the mean. It wants to be almost sure that the sample mean is within plus or minus 1 point of the true population mean value. How large, n will the random sample have to be

81 samples

Step-by-step explanation:

According to the empirical rule :

Possible values of the sample mean is within 3 standard deviations of the population mean :

μ ± 3 sd(x) ; sd(x) = standard deviation of sampling distribution.

3 * sd(x) = 1

sd(x) = 1/3

Recall:

Standard deviation of sampling distribution, sd(x)

sd(x) = σ / sqrt(n)

1/3 = 3 / sqrt(n)

Square both sides

1/9 = 9/n

Cross multiply :

n * 1 = 9 * 9

n = 81

3. parallelogram

step-by-step explanation:

we turn each of our sides into direction vectors

ab=b-a=(3 - 7, 1 - 0) = (-4, 1)

bc=c-b=(1,6)

cd=d-c=(4,-1)

da=a-d=(-1,-6)

we see how the opposite sides have negated direction vectors; this is characteristic of a parallelogram.   we have congruent sides ab=cd and bc=da with unequal lengths because 1^2+6^2 is different from (-4)^2+1^2.   so it's not a square or a rhombus.  

we check the dot product of direction vectors of adjacent sides.   we have

ab dot bc = -4(1) + 1(6) = 2

that's not zero so the sides are not perpendicular.   we've ruled out rectangle.

the direction vectors indicate two pairs of congruent parallel sides, so we choose parallelogram over trapezoid.

the answer is a

step-by-step explanation: