Answer:
Option 1: CD is a perpendicular bisector of AB
Step-by-step explanation:
Let us find out the slopes of various line segments and the Distances and then we will draw the conclusions accordingly.
Formula to find slope

Formula to Find Distance between two points

mAB ( represents , Slope of AB )
1. 
2. 
3. 
4. 
5. 
mAC = mBC , and C is common point , hence these three are collinear points making a straight line whole slope is 



Hence CD ⊥ AB
Also
From Point 4 and point 5 above , we see that
AC = CB
Hence CD bisect AB at C, also CD ⊥ AB
There fore
CD is a perpendicular bisector of AB
Therefor option 1 is true
Answer:
We need a sample size of at least 719
Step-by-step explanation:
We have that to find our
level, that is the subtraction of 1 by the confidence interval divided by 2. So:

Now, we have to find z in the Ztable as such z has a pvalue of
.
So it is z with a pvalue of
, so 
Now, find the margin of error M as such

In which
is the standard deviation of the population and n is the size of the sample.
How large a sample size is required to vary population mean within 0.30 seat of the sample mean with 95% confidence interval?
This is at least n, in which n is found when
. So






Rouding up
We need a sample size of at least 719
To find the expected value of the distribution, we multiply each outcome by it's probability. Doing this, we get that the expected value of defects on a skateboard is of
.
Outcomes and probabilities:
0 defects, 9/10 probability
1 defect, 1/20 probability
2 defects, 1/25 probability
3 defects, 1/100 probability.
Expected value:

Dividing both numerator and denominator by 4:

Thus, the expected value of defects on a skateboard is of
.
A similar problem is given at: brainly.com/question/23156292.
He scored 51
explanation:
60 x 0.85 = 51
Every time the line is vertical, the slope is ‘no slope or undefined’.