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Sergeeva-Olga [200]
3 years ago
14

Three-sevenths of a number is 21. Find the number

Mathematics
2 answers:
ruslelena [56]3 years ago
7 0
You can set up a proportion that looks like 3/7 = x/21. X being the number that you are trying to find. Seven goes into 21 three times. So multiply 3 also by that 3 to get 9. So three sevenths of twenty-one is 9.
Softa [21]3 years ago
6 0

Answer:

the answer is 49

Step-by-step explanation:

The question is asking what the original number is. So its not 9. If you do a inverse operation which is 2 divided by 3/7 you get 49. To check your work if you multiply 49 by 3/7 you get 21.

You might be interested in
The angle of depression from the top of a building to a point
AleksandrR [38]

The distance between point on the ground from the top of the building is 396 meter, if the building is 280 m high and The angle of depression from the top of a building to a point  on the ground is 45 degrees.

Step-by-step explanation:

The given is,

                 The angle of depression from the top of a building to a point  on the ground is 45 degrees.

                 Height of the building is 280 meter.

Step: 1

                 Given diagram is a right angled diagram,

                 For right angle triangle,

                              90° = 45° + 45°    

                                     = 90°  

                 Trignometric ratio,

                            sin ∅ = \frac{Opp}{Hyp}....................(1)

                For the above ratio take the bottom angle, that is angle of depression from the top of a building to a point  on the ground is 45 degrees.

                 Where, Opp side = 280 meters

                               Hyp side = x

                                           ∅ = 45°

                 Equation (1) becomes,

                                  sin 45° = \frac{280}{x}

                          0.70710678 =  \frac{280}{x}

                                            x =  \frac{280}{0.70710678}

                                            x = 395.979

               Distance between point on the ground from the top of the building,  x ≅ 396 meter                                                

                Trignometric ratio,

                                     cos ∅ = \frac{Adj}{Hyp}

                                   Cos 45 = \frac{Adj}{396}

                                         Adj = (0.70710678)(396)

              Bottom length, Adj = 280 meter

Result:

           The distance between point on the ground from the top of the building is 396 meter.

8 0
3 years ago
A researcher wishes to​ estimate, with 9090​% ​confidence, the proportion of adults who have​ high-speed Internet access. Her es
Sunny_sXe [5.5K]

Answer:  a) Required minimum sample size= 219

b) Required minimum sample size= 271

Step-by-step explanation:

As per given , we have

Margin of error : E= 5% =0.05

Critical z-value for 90% confidence interval : z_{\alpha/2}=1.645

a) Prior estimate of true proportion: p=28%=0.28

Formula to find the sample size :-

n=p(1-p)(\dfrac{z_{\alpha/2}}{E})^2\\\\=0.28(1-0.28)(\dfrac{1.645}{0.05})^2\\\\=218.213856\approx219

Required minimum sample size= 219

b) If no estimate of true proportion is given , then we assume p= 0.5

Formula to find the sample size :-

n=0.5(1-0.5)(\dfrac{z_{\alpha/2}}{E})^2\\\\=0.25(\dfrac{1.645}{0.05})^2\\\\=270.6025\approx271

Required minimum sample size= 271

8 0
3 years ago
Genuinely confused rn
frosja888 [35]

Using it's concept, it is found that the probability that he winds up wearing the white shirt and tan pants is of \frac{1}{8}.

<h3>What is a probability?</h3>

A probability is given by the <u>number of desired outcomes divided by the number of total outcomes</u>.

In this problem:

  • For the shirt, there is 4 outcomes, hence the probability of the white shirt is 1/4.
  • For the pair of pants, there are 2 outcomes, blue or tan, hence the probability of tan pants is 1/2.

Since the shirt and the pants are independent, the probability is given by:

p = \frac{1}{4} \times \frac{1}{2} = \frac{1}{8}.

More can be learned about probabilities at brainly.com/question/14398287

#SPJ1

8 0
2 years ago
Is FGH ~ JKL? If so, identify the similarity postulate or theorem that applies.
Leokris [45]
Yes, for triangles to similar two angles have to be the same, in this case, they both have 55 and 30 degrees), this makes the third angle the same. Triangles angles add up to 180 degrees and if you subtract 30 and 55 from 180..
180-30=150-55=95
95+30+55=180

8 1
3 years ago
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What is an equation in point-slope form of the line that passes through the point (4, −1) and has slope 6?
timama [110]
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5 0
3 years ago
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