1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Alinara [238K]
3 years ago
8

How to do answer 16, 19 and 21? Please show me the solutions. ​

Mathematics
2 answers:
Pepsi [2]3 years ago
8 0

Answer:

The speed in still air =  200 mph.

Step-by-step explanation:

21.

If the speed of the plane in still air is  x mph then with the wind its speed is x+20 mph and against the wind it is x - 20 mph. Also let t hours be the time taken for the journey with the wind.

So we have the 2 equations:

x + 20 = 396 / t

x - 20 =  396 / (4 - t)

Subtracting to eliminate  x

40 =   396 / t - 396 / (4 - t)

40t(4 - t) = 396(4 - t) - 396t

160t - 40t^2 = 1584 - 396t - 396t

-40t^2 + 952t  - 1584 = 0

Dividing through by 8:

-5t^2 + 119t - 198 = 0

Using the quadratic formula we get t = 22,  1.8 hours . We ignore the 22 because  the total time is 4 hours.

So the speed x =  is found by plugging in t  1.8:

x + 20 = 396/1.8

x =  200 mph.

Zolol [24]3 years ago
6 0

Answer:

16) the boy is 11 years old

Step-by-step explanation:

16) Let the boy’s present age be b.

b+5 = 4(b-9)^2, or

b+5 = 4[b^2–18b+81] = 4b^2–72b+324, or

4b^2–73b+319 = 0, or

(4b-29)(x-11) = 0, or

b = 11 or 7.25 years. The second value is inadmissible.

So the boy is 11 years old, now.

You might be interested in
1.<br> Find the slope of the line.<br> Ay<br> a) -574<br> b) 5/4<br> c) -4/5<br> d) 4/5
maria [59]

Answer:

a) -5/4

Step-by-step explanation:

Slope is fundamentally rise/run; The points on the line are relative to each other by decreasing/increasing the y-value of +/-5 and decreasing/increasing the x-value by +/-4

The function is decreasing so the slope has to be negative.

The only possible answer choice is -5/4 or a.

3 0
3 years ago
What are the steps on how to copy an angle? (Geometry)
Juli2301 [7.4K]

Step-by-step explanation:

Make a point P that will be the vertex of the new angle.

From P, draw a ray PQ. ...

Place the compasses on point A, set to any convenient width.

Draw an arc across both sides of the angle, creating the points J and K as shown.

Hope this helps :)

4 0
2 years ago
Javier rounded to the nearest half to estimate the product of 3 and two-fifths and Negative 3 and StartFraction 7 over 8 EndFrac
7nadin3 [17]

Answer:

The actual product is less than the estimate. The numbers differ by more than one.

Step-by-step explanation:

i took the test

8 0
3 years ago
Read 2 more answers
Height of a table tennis net: 6 in. height of a tennis net: 3ft
astraxan [27]
The table is 3.5 ft tall
7 0
3 years ago
What is the rate of change for this function? 29. y = 5 ​
Verdich [7]

Correct answer is (0,5)

6 0
2 years ago
Other questions:
  • I'm really confused on this one please answer !!!!!!!
    9·1 answer
  • An ice cream shop's goal is to sell a mean of 45 ice cream cones per day. In one week, it sold the following numbers of ice crea
    13·2 answers
  • If a house is purchased at $240,000, what is the predicted value of the house in 12 years if it appreciates at a rate of 4% per
    5·2 answers
  • What is 2 + 2, times 12, plus 9, divided by 1200, multiplied by 6, minus 12,000,000, divided by 4, plus 26, times 9, times 8, ti
    14·1 answer
  • Whats number 7?? im so confused!!
    6·1 answer
  • 11.1 billion dollars is spent on line over the Thanksgiving weekend. An amount that is equal to 1.05% of that is given to charit
    11·2 answers
  • Isabella wants to put a fence around her pumpkin patch.
    8·1 answer
  • The sum of the measures of angles for a triangle is 180°. Find the value of x and then the measures of the 3 angles
    6·1 answer
  • Help please :,))))))
    12·1 answer
  • Find a linear inequality with the following solution set. Each grid line represents one unit.
    7·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!