7sec...........................................................................
Answer:
Trapezoid
Step-by-step explanation:
Given quadrilateral has vertices at points A(-2,-1), B(3,13), C(15,5) and D(13,-11).
Find slopes of lines AD and BC:

Since the slopes are the same, lines AD and BC are parallel.
Find slopes of lines ABD and CD:

Since the slopes are different, lines AB and CD are not parallel.
This means quadrilateral ABCD is trapezoid (two opposite sides - parallel and two another opposite sides - not parallel)
Answer: a) 27.5, b) 5.33.
Step-by-step explanation:
Since we have given that

and n = 180
We need to calculate the sample mean and sample standard deviation.
So, the mean of the distribution of sample means is

The standard deviation of the distribution of sample means is

Hence, a) 27.5, b) 5.33.
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