Answer:
Step-by-step explanation:
Hello!
The variable of interest is
X: Weight of a male baby (pounds)
X~N(μ;σ²)
μ= 11.5 pounds
σ= 2.7 pounds
a) Find the 81st percentile of the baby weights.
This percentile is the value that separates the bottom 81% of the distribution from the top 19%
P(X≤x₁)= 0.81
For this you have to use the standard normal distribution. First you have to look the 81st percentile under the Z distribution and then "translate" it to a value of the variable X using the formula Z= (X- μ)/σ
P(Z≤z₁)= 0.81
z₁= 0.878
z₁= (x₁- μ)/σ
z₁*σ= x₁- μ
(z₁*σ) + μ= x₁
x₁= (z₁*σ) + μ
x₁= (2.7*0.878)+11.5
x₁= 13.8706 pounds
b) Find the 10th percentile of the baby weights.
P(X≤x₂)= 0.10
P(Z≤z₂)= 0.10
z₂= -1.282
z₂= (x₂- μ)/σ
z₂*σ= x₂- μ
(z₂*σ) + μ= x₂
x₂= (z₂*σ) + μ
x₂= (2.7*-1.282)+11.5
x₂= 8.0386 pounds
c) Find the first quartile of the baby weights.
P(X≤x₃)= 0.25
P(Z≤z₃)= 0.25
z₃= -0.674
z₃= (x₃- μ)/σ
z₃*σ= x₃- μ
(z₃*σ) + μ= x₃
x₃= (z₃*σ) + μ
x₃= (2.7*-0.674)+11.5
x₃= 9.6802 pounds
I hope this helps!
Answer:
a and b
Step-by-step explanation:
The length is 30 meters and the width is 12 meters.
Answer:
Part A. At least 6 hours
Part B. In less than 2.5 hours Elijah will be behind Mercedes
Part C. In more than 2.5 hours Elijah will be ahead Aubrey
Step-by-step explanation:
D = distance
v =speed
t = time
Formula connecting D, v and t:

Part A.
Steve's speed: 
Distance: at least 21 miles
Time: unknown, so
![3.5\cdot t\ge 21\\ \\35t\ge 210\ [\text{Multiplied by 10}]\\ \\t\ge \dfrac{210}{35}\\ \\t\ge \dfrac{30}{5}\\ \\t\ge 6](https://tex.z-dn.net/?f=3.5%5Ccdot%20t%5Cge%2021%5C%5C%20%5C%5C35t%5Cge%20210%5C%20%5B%5Ctext%7BMultiplied%20by%2010%7D%5D%5C%5C%20%5C%5Ct%5Cge%20%5Cdfrac%7B210%7D%7B35%7D%5C%5C%20%5C%5Ct%5Cge%20%5Cdfrac%7B30%7D%7B5%7D%5C%5C%20%5C%5Ct%5Cge%206)
It would take Steve at least 6 hours to walk at least 21 mi on Day 1.
Part B.
Mercedes's speed: 
Elijan's speed: 
Elijan's Distance walked:
miles
Mercedes's Distance walked:
miles
Time: x hours
Mercedes is 2 miles ahead, so

Elijan will be behind when

In 2.5 hours Elijan will catch up Mercedes, and in less than 2.5 hours Elijah will be behind Mercedes.
Part C.
Aubrey's speed: 
Elijan's speed: 
Elijan's Distance walked:
miles
Aubrey's Distance walked:
miles
Time: x hours
At the beginning of Day 3, Elijah starts walking at the marker for Mile 42, and Aubrey starts walking at the marker for Mile 42.5.

Elijan will be ahead of Aubrey when
![D_E>D_A\\ \\42+3.2x> 42.5+3x\\ \\3.2x-3x>42.5-42\\ \\0.2x>0.5\\ \\2x>5\ [\text{Multiplied by 10}]\\ \\x>\dfrac{5}{2}\\ \\x>2.5\ hours](https://tex.z-dn.net/?f=D_E%3ED_A%5C%5C%20%5C%5C42%2B3.2x%3E%2042.5%2B3x%5C%5C%20%5C%5C3.2x-3x%3E42.5-42%5C%5C%20%5C%5C0.2x%3E0.5%5C%5C%20%5C%5C2x%3E5%5C%20%5B%5Ctext%7BMultiplied%20by%2010%7D%5D%5C%5C%20%5C%5Cx%3E%5Cdfrac%7B5%7D%7B2%7D%5C%5C%20%5C%5Cx%3E2.5%5C%20hours)
In 2.5 hours Elijan will catch up Aubrey, and in more than 2.5 hours Elijah will be ahead Aubrey.