We have been given for a normal distribution the mean time it takes to walk to the bus stop is 8 minutes with a standard deviation of 2 minutes. And the mean time it takes for the bus to get to school is 20 minutes with a standard deviation of 4 minutes.
(a) Average time that it would take reach school can be obtained by adding the average times.
8+20 = 28 minutes.
(b) Standard deviation of the trip to school can be found as:
Therefore, standard deviation of the entire trip is 4.47 minutes.
(c) Let us first find z score corresponding to 30 minutes.
We need to find the probability such that 
Therefore, the required probability is 0.67.
(d) If average time to walk to school is 10 minutes, then overall average time for the trip will be 10+20 = 30 minutes.
(e) Standard deviation won't change it will remain 4.47
(f) The new probability will be:
Therefore, probability will be 0.50.
Answer: B) Dilate by scale factor of 2
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Explanation:
Your teacher isn't saying this directly, but I'm assuming s/he wants you to find a similar figure that isn't congruent to the original. Informally, your teacher seems to want you to find a figure that is the same shape but not the same size as the original.
If so, then any dilation will shrink or enlarge the image depending on the scale factor. So the new image will not be the same as the old one. In this case, a dilation with scale factor 2 means the new figure is twice as large (each side is twice as long). But the old image is similar to the new image. The angles keep their values and therefore we get the same shape. This is why choice B is the answer. Again this is assuming what I mentioned in the first paragraph.
Choices A, C, and D are all known as rigid transformations and they preserve the same size of the figure. Applying any of those operations will lead to the same figure (just rotated, reflected or shifted somehow). In other words, applying operations A,C, or D will have us get two congruent triangles. If two triangles are congruent, then they are automatically similar, but not vice versa. This is why we can rule out A,C, and D.
Answer:
y = -0.07x2 + 3.07x
Step-by-step explanation:
For each plant we add, there is a decrease of 70 grams for all plants from the inicial value of 3 kg of beans.
So, for 2 plants, we have (3 - 0.07) * 2
For 3 plants, we have (3 - 2*0.07) * 3
For x plants, we have (3 - (x-1)*0.07) * x
So we can model the final result of the amount of beans 'y' with the equation:
y = (3 - (x-1)*0.07) * x
y = (3 - 0.07x + 0.07) * x
y = (3.07 - 0.07x) * x
y = -0.07x2 + 3.07x
(In this equation we have a = -0.07, b = 3.07 and c = 0)
For this case we have the following polynomial:
7x2 + 68xy - 20y2
Factoring we have:
(7x-2y) (x + 10y)
We verify the factorization:
7x2 + 70xy - 2xy - 20y2
Rewriting we have:
7x2 + 68xy - 20y2
Therefore, the factorization is correct.
Answer:
A) (7x - 2y) (x + 10y)
I don't really know if this is correct but I think it is x+y+z=14
