Answer:
a) 229 and 305 days
b) 229 days or less
c) 305 days or more
Step-by-step explanation:
The Empirical Rule(68-95-99.7 rule) states that, for a normally distributed random variable:
68% of the measures are within 1 standard deviation of the mean.
95% of the measures are within 2 standard deviation of the mean.
99.7% of the measures are within 3 standard deviations of the mean.
In this problem, we have that:
Mean = 267
Standard deviation = 19
(a) Between what values do the lengths of the middle 95% of all pregnancies fall?_____________and___________days
By the Empirical rule, 95% of all pregnancies fall within 2 standard deviations of the mean.
So
267 - 2*19 = 229 days
to
267 + 2*19 = 305 days
(b) How short are the shortest 2.5% of all pregnancies?______days or less
95% of all pregnancies fall within 2 standard deviations of the mean. The other 5% are more than 2 standard deviations from the mean. Since the distribution is symmetric, 2.5% is more than 2 standard deviations below the mean(shortest 2.5%) and 2.5% is more than 2 standard deviations above the mean(longest 2.5%). So
267 - 2*19 = 229 days
c) How long do the longest 2.5% of pregnancies last?________days or more
Explanation in b)
267 + 2*19 = 305 days
Answer:
m(∠C) = 18°
Step-by-step explanation:
From the picture attached,
m(arc BD) = 20°
m(arc DE) = 104°
Measure of the angle between secant and the tangent drawn from a point outside the circle is half the difference of the measures of intercepted arcs.
m(∠C) = ![\frac{1}{2}[\text{arc(EA)}-\text{arc(BD)}]](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7B2%7D%5B%5Ctext%7Barc%28EA%29%7D-%5Ctext%7Barc%28BD%29%7D%5D)
Since, AB is a diameter,
m(arc BD) + m(arc DE) + m(arc EA) = 180°
20° + 104° + m(arc EA) = 180°
124° + m(arc EA) = 180°
m(arc EA) = 56°
Therefore, m(∠C) = 
m(∠C) = 18°
If anything is above 5 it will round up
Answer:
(x, y) = (-0.6, 0.8) or (1, 4)
Step-by-step explanation:
Use the second equation to substitute for y in the first.
(x -1)² +((2x +2) -2)² = 4
x -2x +1 + 4x² = 4 . . . . . . . eliminate parentheses
5x² -2x -3 = 0 . . . . . . . . . . subtract 4, collect terms
Now we can rearrange the middle term to ease factoring by grouping.
(5x² -5x) +(3x -3) = 0
5x(x -1) +3(x -1) = 0
(5x +3)(x -1) = 0
The values of x that make these factors zero are ...
x = -3/5, x = 1
The corresponding values of y are ...
y = 2(-3/5)+2 = 4/5 . . . . for x = -3/5
y = 2(1) +2 = 4 . . . . . . . . for x = 1
The solutions are: (x, y) = (-3/5, 4/5) or (1, 4).
___
A graphing calculator verifies these solutions.