Answer:
The proportion of infants with birth weights between 125 oz and 140 oz is 0.1359 = 13.59%.
Step-by-step explanation:
When the distribution is normal, we use the z-score formula.
In a set with mean 
and standard deviation 
, the zscore of a measure X is given by:
The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.
In this question, we have that:
The proportion of infants with birth weights between 125 oz and 140 oz is
This is the pvalue of Z when X = 140 subtracted by the pvalue of Z when X = 125. So
X = 140
has a pvalue of 0.9772
X = 125
has a pvalue of 0.8413
0.9772 - 0.8413 = 0.1359
The proportion of infants with birth weights between 125 oz and 140 oz is 0.1359 = 13.59%.
Answer:
3%
Step-by-step explanation:
This equation represents exponential decay. Whenever the base is less than 1, the function represents decay. When the base is greater than 1, the function represents growth. In this case, the base is .97 which is less than 1, representing decay.
The formula for exponential decay is y=a(1-r)x.
r is the decay rate, expressed as a decimal.
In this case, r = .03 which represents 3%!
Problem 1
1a) Jon created a torus while Nadia created a cone. A torus is basically a donut shaped 3D object. You can think of it as a 3D inflatable pool ring (lifeguard pool ring), or one of the rings from the game of ring toss.
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1b) Each plane of symmetry that Nadia points out is a plane that runs through points B and C. In a similar manner, Jon has the same plane of symmetry. Both have infinitely many planes of symmetry of this nature.
For Jon, his torus or donut shaped object can be cut in half along the horizontal axis. Imagine cutting a bagel so you can apply cream cheese or butter or whatever item you like. Each half of the bagel would be congruent to one another. This is the "plus 1" Jon is talking about.
This horizontal cut cannot be applied to Nadia's cone. If she were to cut her cone anywhere along a horizontal plane then she'd have a frustum at the bottom and a smaller cone up top (instead of two congruent smaller cones)
note: to be fair, infinity+1 is the same as infinity. They both describe the idea of listing numbers forever. We can add any number to infinity to get infinity.
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Problem 2
2a) To reflect over the xz plane, we keep the x and z coordinates the same. Only the y coordinate flips from positive to negative (or vice versa). For instance, the point P(0,5,4) becomes P'(0,-5,4) after such a reflection.
The algebraic way to write the rule is
(x,y,z) ---> (x,-y,z)
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2b) After applying the reflection rule, you should get the following
P(0,5,4) ---> P ' (0,-5,4)
Y(-2,7,4) ---> Y ' (-2,-7,4)
R(0,7,4) ---> Y ' (0,-7,4)
A(0,7,6) ---> Y ' (0,-7,6)
Once again, only the y value is changing. The sign of the y value specifically.
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2c) It's not entirely clear what your teacher means by "back", "left" and "up". Why is that? Because there are at least 2 different ways to orient the xyz axis.
One such way is to have the z axis sticking up and have the xy axis as the "floor" so to speak. Another way is to have the z axis come out of the board and have the y axis sticking up (so the xy axis is flat against the wall).
Concepts of "left", "right", "up", "down", etc are all relative to your frame of reference. One person's "up" is another person's "down". Unfortunately I don't think there's enough info to solve here. It would have been much more ideal if your teacher said something like "3 units along the x axis" rather than "3 units back".
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2d) See part C above. There isn't enough info (at least, in my opinion anyway).
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Problem 3
3a) A cylinder forms. The rectangle RECT is basically a revolving door. When you spin the revolving door really fast, it leads to the illusion of a 3D cylindrical block. You can also picture a propeller fan to visualize the same basic idea. This cylinder has a height of TC = 3 units. The radius is EC = 5 units.
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3b)
From part A, r = radius = 5, h = height = 3
SA = 2*pi*r^2 + 2*pi*r*h
SA = 2*pi*5^2 + 2*pi*5*3
SA = 50*pi + 30*pi
SA = 80*pi <--- exact surface area
SA = 251.3274 <--- approx surface area
surface area is in square units
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3c)
Use the same dimensions (r = 5, h = 3) from part B
V = pi*r^2*h
V = pi*5^2*3
V = pi*25*3
V = pi*75
V = 75*pi <--- exact volume
V = 235.6194 <--- approx volume
volume is in cubic units
