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Elis [28]
3 years ago
12

Which of the following is true about a parallelogram? A. Opposite angles of a parallelogram are not congruent. B. Parallelograms

always have four congruent sides. C. Only two sides of a parallelogram are parallel. D. The diagonals of a parallelogram always bisect each other.
Mathematics
1 answer:
mafiozo [28]3 years ago
5 0

Answer: The option is D.

Step-by-step explanation:

A line that intersects another line segment and separates it into two equal parts is called a bisector.

In a quadrangle, the line connecting two opposite corners is called a diagonal. We will show that in a parallelogram, each diagonal bisects the other diagonal.

Problem

ABCD is a parallelogram, and AC and BD are its two diagonals.  Show that AO = OC and that BO = OD

Strategy

Once again, since we are trying to show line segments are equal, we will use congruent triangles. And here, the triangles practically present themselves. Let’s start with showing that AO is equal in length to OC, by using the two triangles in which AO and OC are sides: ΔAOD and  ΔCOB.

There are all sorts of equal angles here that we can use. Several pairs of (equal) vertical angles, and several pairs of alternating angles created by a transversal line intersecting two parallel lines. So finding equal angles is not a problem. But we need at least one side, in addition to the angles, to show congruency.

As we have already proven, the opposite sides of a parallelogram are equal in size, giving us our needed side.

Once we show that ΔAOD and  ΔCOB are congruent, we will have the proof needed, not just for AO=OC, but for both diagonals, since BO and OD are alsocorresponding sides of these same congruent triangles.

ABCD is a parallelogram    

Given

AD || BC                                

From the definition of a parallelogram

AD = BC                                 Opposite sides of a parallelogram are equal in size

∠OBC ≅ ∠ODA                      Alternate Interior Angles Theorem, ∠OCB ≅ ∠OAD                      Alternate Interior Angles Theorem,

ΔOBC ≅ ΔODA                     

Angle-Side-Angle

BO=OD                                Corresponding sides in congruent triangles AO=OC                             Corresponding sides in congruent triangles.

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According to Padgett Business Services, 20% of all small-business owners say the most important advice for starting a business i
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Answer:

a) There is a 6.88% probability that none of the owners would say preparing for long hours and hard work is the most important advice.

b) There is a 1.93% probability that six or more owners would say preparing for long hours and hard work is the most important advice.

c) There is a 10.32% probability that exactly five owners would say having good financing ready is the most important advice.

d) The expected number of owners who would say having a good plan is the most important advice is 2.28

Step-by-step explanation:

Questions a), b), c) are all solved as binomial distribution problems.

Question d) is a simple calculation.

Binomial probability distribution

The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.

P(X = x) = C_{n,x}.\pi^{x}.(1-\pi)^{n-x}

In which C_{n,x} is the number of different combinatios of x objects from a set of n elements, given by the following formula.

C_{n,x} = \frac{n!}{x!(n-x)!}

And \pi is the probability of X happening.

For these problems

12 business owners were contacted, so n = 12.

a. What is the probability that none of the owners would say preparing for long hours and hard work is the most important advice?

20% of all small-business owners say the most important advice for starting a business is to prepare for long hours and hard work, so \pi = 0.2.

That is P(X=0) when \pi = 0.2.

P(X = x) = C_{n,x}.\pi^{x}.(1-\pi)^{n-x}

P(X = 0) = C_{12,0}.(0.2)^{0}.(0.8)^{12} = 0.0688

There is a 6.88% probability that none of the owners would say preparing for long hours and hard work is the most important advice.

b. What is the probability that six or more owners would say preparing for long hours and hard work is the most important advice?

20% of all small-business owners say the most important advice for starting a business is to prepare for long hours and hard work, so \pi = 0.2.

This is:

P = P(X = 6) + P(X = 7) + P(X = 8) + P(X = 9) + P(X = 10) + P(X = 11) + P(X = 12)

P(X = x) = C_{n,x}.\pi^{x}.(1-\pi)^{n-x}

P(X = 6) = C_{12,6}.(0.2)^{6}.(0.8)^{6} = 0.0155

P(X = 7) = C_{12,7}.(0.2)^{7}.(0.8)^{5} = 0.0033

P(X = 8) = C_{12,8}.(0.2)^{8}.(0.8)^{4} = 0.0005

P(X = 9) = C_{12,9}.(0.2)^{9}.(0.8)^{3} = 0.00006

P(X = 10) = C_{12,10}.(0.2)^{10}.(0.8)^{2} = 0.000004

P(X = 11) = C_{12,11}.(0.2)^{11}.(0.8)^{1} = 0.0000002

P(X = 12) = C_{12,12}.(0.2)^{12}.(0.8)^{0} = 0.000000004

So:

P = P(X = 6) + P(X = 7) + P(X = 8) + P(X = 9) + P(X = 10) + P(X = 11) + P(X = 12) = 0.0155 + 0.0033 + 0.0005 + 0.000006 + 0.000004 + 0.0000002 + 0.000000004 = 0.0193

There is a 1.93% probability that six or more owners would say preparing for long hours and hard work is the most important advice.

c. What is the probability that exactly five owners would say having good financing ready is the most important advice?

Twenty-five percent say the most important advice is to have good financing ready, so \pi = 0.25

P(X = x) = C_{n,x}.\pi^{x}.(1-\pi)^{n-x}

P(X = 5) = C_{12,5}.(0.25)^{5}.(0.75)^{7} = 0.1032

There is a 10.32% probability that exactly five owners would say having good financing ready is the most important advice.

d. What is the expected number of owners who would say having a good plan is the most important advice?

Nineteen percent say having a good plan is the most important advice, so that is 0.19*12 = 2.28

The expected number of owners who would say having a good plan is the most important advice is 2.28

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