Let x = the width
then
2x = the length
:
The box dimensions: 2x by x by 4
Given the surface area:
2(2x*x) + 2(2x*4) + 2(x*4) = 220
:
4x^2 + 16x + 8x = 220
A quadratic equation:
4x^2 + 24x - 220 = 0
simplify, divide by 4
x^2 + 6x - 55 = 0
Factor
(x+11)(x-5) = 0
The positive solution is what we want here:
x = 5 ft is the width
then
2(5) = 10 ft is the length
:
Find the volume
10 * 5 * 4 = 200 cu/ft is the volume
Answer:
no i don't think so
Step-by-step explanation:
Answer: 547
Step-by-step explanation: The margin of error formulae is given below as
Margin of error = critical value ×(σ/√n)
Where σ = standard deviation and n is the sample size.
From our question, margin of error = 0.08
Variance is 1.691,
hence σ = √variance = √1.691
= 1.3.
We will be using a z test for our critical value this is because a soft drink manufacturer will always produce drinks more than 30 in numbers.
The critical value for a 85% confidence interval is 1.44.
Hence critical value is 1.44.
By substituting the parameters, we have that
0.08 = 1.44 × 1.3/ √n
0.08 = 1.873/ √n
By cross multiplying
0.08 × √n = 1.873
√n = 1.873/ 0.08
√n = 23.41
n = (23.41)²
n = 547.
Speed of the plane: 250 mph
Speed of the wind: 50 mph
Explanation:
Let p = the speed of the plane
and w = the speed of the wind
It takes the plane 3 hours to go 600 miles when against the headwind and 2 hours to go 600 miles with the headwind. So we set up a system of equations.
600
m
i
3
h
r
=
p
−
w
600
m
i
2
h
r
=
p
+
w
Solving for the left sides we get:
200mph = p - w
300mph = p + w
Now solve for one variable in either equation. I'll solve for x in the first equation:
200mph = p - w
Add w to both sides:
p = 200mph + w
Now we can substitute the x that we found in the first equation into the second equation so we can solve for w:
300mph = (200mph + w) + w
Combine like terms:
300mph = 200mph + 2w
Subtract 200mph on both sides:
100mph = 2w
Divide by 2:
50mph = w
So the speed of the wind is 50mph.
Now plug the value we just found back in to either equation to find the speed of the plane, I'll plug it into the first equation:
200mph = p - 50mph
Add 50mph on both sides:
250mph = p
So the speed of the plane in still air is 250mph.
