Answer:
a) 20.16; b) 20.49 and 21.51
Step-by-step explanation:
We use z scores for each of these. The formula for a z score is
.
For part a, we want the 20th percentile; this means we want 20% of the data to be lower than this. We find the value in the cells of the z table that are the closest to 0.20 as we can get; this is 0.2005, which corresponds with a z score of -0.84.
Using this, 21 as the mean and 1 as the standard deviation,
-0.84 = (X-21)/1
-0.84 = X-21
Add 21 to each side:
-0.84+21 = X-21+21
20.16 = X
For part b, we want the middle 39%. This means we want 39/2 = 19.5% above the mean and 19.5% below the mean; this means we want
50-19.5 = 30.5% = 0.305 and
50+19.5 = 69.5% = 0.695.
Looking these values up in the cells of the z table, we find those exact values; 0.305 corresponds with z = -0.51 and 0.695 corresponds with z = 0.51:
-0.51 = (X-21)/1
-0.51 = X-21
Add 21 to each side:
-0.51+21 = X-21+21
20.49 = X
0.51 = (X-21)/1
0.51 = X-21
Add 21 to each side:
0.51+21 = X-21+21
21.51 = X
Answer: 27.97 i thin is the answer
Step-by-step explanation:
Answer:
1
C = --------
a¹² b⁸
Step-by-step explanation:
(a⁻³/b²)⁴
( (1/a³) / (b²))⁴
( 1/a³ ÷ b² )⁴
therefore,
1
= ------
a¹² b⁸
This is how I did it:
use distribution
use addition
use addition and subtraction
use division
So your answer is
X + 2y = 8
x = -2y + 8....so we sub -2y + 8 for x in the other equation
2x + y = 7
2(-2y + 8) + y = 7
-4y + 16 + y = 7
-3y = 7 - 16
-3y = - 9
y = -9/-3
y = 3
x = -2y + 8
x = -2(3) + 8
x = -6 + 8
x = 2
solution is (2,3)