A standardized exam's scores are normally distributed. In a recent year, the mean test score was 1473 and the standard deviation was 318 . The test scores of four students selected at random are 1890 , 1230 , 2220 , and 1360 . Find the z-scores that correspond to each value and determine whether any of the values are unusual.

Z score ( X = 1890 ): 1.31

Z score ( X = 1230 ): -0.76

Z score ( X = 2220 ): 2.34 (This value of Z is unusual )

Z score ( X = 1360 ): -0.35

Step-by-step explanation:

Here we have  , A standardized exam's scores are normally distributed. In a recent year, the mean test score was 1473 and the standard deviation was 318 . The test scores of four students selected at random are 1890 , 1230 , 2220 , and 1360 . We need to find Find the z-scores that correspond to each value and determine whether any of the values are unusual. Let's find out:

We know that Z score is given by : ( data - Mean ) / ( standard deviation )

Z score ( X = 1890 ):

⇒

Z score ( X = 1230 ):

⇒

Z score ( X = 2220 ):

⇒

This value of Z is unusual as Value lies as : .

Z score ( X = 1360 ):

⇒

trapezoid

step-by-step explanation:

first i plotted all my points on a grid graph

i made sure all of them were in the correct quadrant

then i saw it was a trapezoid or a quadrilateral

the graph in the attached figure

step-by-step explanation:

we have

using a graphing tool

the graph in the attached figure

the roots are ( x-intercepts) x=-0.5,x=1,x=3

the y-intercept is the point (0,3)