Answer:
The estimate is about 47
Step-by-step explanation:
45.67 ~ 45.5
1.42 ~ 1.5
1.5 + 45.5 = 47
Looks good to me. Calculation is correct. Although you might want to add to #1 your description; that the width of the rectangle is the circumference of the circle (w = 2πr) and that you add the surfaces together to get the total surface area.
total surface area = area of rectangular part + area of circular parts
SA = 2πrL + 2πr²
Width =3.5, length = 4
Let's make a few equations to summarize what we know.:
a = 14
l = 2w -3
a = wl
Now let's substitute the expression for l into the expression for area and solve.
a = w(2w - 3)
a = 2w^2 - 3w
14 = 2w^2 - 3w
0 = 2w^2 - 3w - 14
which factors into
(2w - 7) (w + 2)
Solving for w
2w - 7 = 0
2w = 7
w = 3.5
w+2 = 0
w = -2
So w can be either 3.5 or -2. Since a negative width doesn't make sense, w = 3.5
Let's verify
w = 3.5
l = 2w - 3
l = 2*3.5 - 3
l = 7 - 3
l = 4
a = wl
a = 3.5 * 4
a = 14
So the width is 3.5 and the length is 4.
It would be: 18/15 * 100 = 1800/15 = 120%
Mph is what you are going for
so 171/3 = 57
57mph is your answer
hope this helps
