The standard deviation of what? Percentiles from any normal distribution look the same, just like the unit normal, so you can't really determine the standard deviation of the original scores. You can determine a z score from a percentile. That tells us the number of standard deviations, positive or negative, a given score is away from the mean score. It's a normalized test result.
Your percentile is (a hundred times) the probability that another score is less than your score. We have a normal distribution, so that probability is the integral of the standard normal from negative infinity to our normalized score.
Let's call the percentile rank

, already scaled between zero and 1.

corresponds to a z score

because the fiftieth percentile means we got an exactly average score, 0 standard deviations away from the mean.
We know 68% of the probability will be between -1 and +1 standard deviation. So

corresponds to

and

corresponds to

Similarly, 95% of the probability will be between -2 and +2 standard deviations. So

corresponds to

and

corresponds to

That's about the list I can do off the top of my head. I think three standard deviations is 99.7%. For the rest we just consult a z table or integrated normal table. We find p in the body of the table (maybe |.5-p| depending on the table) and then the column headings tell us our z score.
In this modern age, your computer can do this for you quickly
Answer:
The porch is 17 ft by 17 ft
Step-by-step explanation:
The perimeter of a square is
P = 4s where s is the side length
P = 4( 3x+2)
P = 12x+8
We know P = 14x-2
14x-2 = 12x+8
Subtract 12x from each side
14x-2 -12x = 12x+8-12x
2x -2 = 8
Add 2 to each side
2x-2 +2 = 8+2
2x= 10
Divide by 2
2x/2 = 10/2
x = 5
The side is 3x+2
3*5+2
15+2
17
The porch is 17 ft by 17 ft
Answer:
1st one jus did this
Step-by-step explanation:
easy
Answer:
180 square units I hope it will help you please follow me
For the first one, you did good. I will just suggest a couple things.
Statement Reason
JK ≅ LM Given
<JKM ≅ < LMK Given (You did both of these steps so well done.)
MK ≅ MK Reflexive Property (Your angle pair is congruent but isn't one of the interior angle of the triangles you are trying to prove.)
ΔJMK ≅ ΔLKM SAS
Problem 2: (You also have a lot of great stuff here.)
Statement Reason
DE ║ FG Given
DE ≅ FG Given
<DEF≅<FGH Given
<EDF≅<GFH Corresponding Angles (You don't need to know that F is the midpoint but you got corresponding angle pair which is correct.)
ΔEDF≅ΔGFH ASA
<DFE≅<FHG CPCTC