Short Answer: 18 minutes
Remark
The answer to this problem is less than the smallest time of the two people working together. that fact lets out C and D (38 minutes and 75 minutes). Now you have to choose 15 minutes and 18 minutes. There's a method. No guessing needed.
Givens
Let the time for Sophie = S
Let the time for Simon = M
Let the job to completion = 1
S = 45 minutes
M = 30 minutes
Step One
Convert minutes to hours.
45 minutes = 45 / 60 = 3/4 hour = 0.75 hour
30 minutes = 30 / 60 = 1/2 hour = 0.50 hour
Step Two
Set up the Equation
The formula is a form of job / hour.
Let the time = t that they both have to work
job = 1 in these problems.
1/S + 1/M = 1/t
1/0.75 + 1/0.5 = 1/t
Solve
1 ÷ 0.75 = 1.33333
1 ÷ 0.5 = 2
1.3333 + 2 = 3.33333
3.3333 = 1 / t Multlply both sides by t
3.3333*t = 1
t = 1 / 3.333333333
t = 0.3 of an hour
1 hour = 60 minutes
0.3 hours = x Cross Multiply
x = 60 * 0.3
x = 18 minutes
Answer working together it took them 18 minutes <<<<<
Answer: The percentile is 89
Step-by-step explanation:
This question can be solved using concept for t tables
In a normal distribution the curve. 
The relationship between z score, mean and standard deviation is given by
So the z value according to this is given by the formula
From the z table we can infer that p value for z=+1.217 is 88.82
So 1750 is 89th percentile
To learn more about statistics, visit brainly.com/question/26352252
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Answer:
d. 18x^3-27x^2y
Step-by-step explanation:
(3x)^2(2x-3y)
work out the first term
9x^2(2x-3y)
distribute
18x^3-27x^2y
Answer:
A(max) = (9/2)*L² ft²
Dimensions:
x = 3*L feet
y = (3/2)*L ft
Step-by-step explanation:
Let call "x" and " y " sides of the rectangle. The side x is parallel to the wall of the house then
Area of the rectangle is
A(r) = x*y
And total length of fence available is 6*L f , and we will use the wall as one x side then, perimeter of the rectangle which is 2x + 2y becomes x + 2*y
Then
6*L = x + 2* y ⇒ y = ( 6*L - x ) /2
And the area as function of x is
A(x) = x* ( 6*L - x )/2
A(x) = ( 6*L*x - x² ) /2
Taking derivatives on both sides of the equation we get:
A´(x) = 1/2 ( 6*L - 2*x )
A´(x) = 0 ⇒ 1/2( 6*L - 2*x ) = 0
6*L - 2*x = 0
-2*x = - 6*L
x = 3*L feet
And
y = ( 6*L - x ) /2 ⇒ y = ( 6*L - 3*L )/ 2
y = ( 3/2)*L feet
And area maximum is:
A(max) = 3*L * 3/2*L
A(max) = (9/2)*L² f²
