The ages of ten employees at a small company are shown below. 30, 32, 35, 35, 38, 38, 38, 40, 40, 45

If the data set were expanded to include a new employee who is 20 years old, how would the mean of the data set change?

A) The mean decreases by 2 years.
B) The mean decreases by about I .6 years.
C) The mean increases by about 1.6 years.
D) The mean does not change.

B

Step-by-step explanation:

Before you add 20 the mean is 37.1 after you add 20 it’s 35.54.

37.1-35.54=1.56

Round 1.56 to 1.6

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.

its totaly b

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