Answer:
0.67 cm/s
Step-by-step explanation:
The area of a square is given by :
....(1)
Where
x is the side of a square
Differentiating equation (1) wrt t.
When A = 81cm², the side of the square, x = 9 cm
Put all the values,
So, the length of the side of a square is changing at the rate of 0.67 cm/s.
This value is approximate.
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Explanation:
Let's compute the z score for x = 40
z = (x-mu)/sigma
z = (40-47)/7
z = -1
We're exactly one standard deviation below the mean.
Repeat these steps for x = 68
z = (x-mu)/sigma
z = (68-47)/7
z = 3
This score is exactly three standard deviations above the mean.
Now refer to the Empirical Rule chart below. We'll add up the percentages that are between z = -1 and z = 3. This consists of the two pink regions (each 34%), the right blue region (13.5%) and the right green region (2.35%). These percentages are approximate.
34+34+13.5+2.35 = 83.85
<u>Roughly 83.85%</u> of the one-mile roadways have between 40 and 68 potholes.
