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
zubka84 [21]
3 years ago
15

When an opinion poll calls landline telephone numbers at random, approximately 30% of the numbers are working residential phone

numbers. The remainder are either non-residential, non-working, or computer/fax numbers. You watch the random dialing machine make 20 calls. What is the mean number of calls that reach a person? Standard deviation?
Mathematics
1 answer:
ioda3 years ago
8 0

Answer:

Mean = 6

Standard Deviation = 4.2

Step-by-step explanation:

This is a binomial probability distribution problem.

The mean has formula:

\mu = np

The standard deviation has formula:

\sigma=np(1-p)

Where n is the number of calls [20]

p is the probability of success [30=0.3]

Let's put these into the formula:

\mu=np\\\mu=(20)(0.3)\\\mu=6

and

\sigma=np(1-p)\\\sigma=(20)(0.3)(1-0.3)\\\sigma=(20)(0.3)(0.7)\\\sigma=4.2

You might be interested in
Help I need help in this geometry question
Rufina [12.5K]
The answer is 8 because I have had that question before so yeah
6 0
3 years ago
Read 2 more answers
Need help fast pls
DanielleElmas [232]
We're given the equation T = 3x + 2.
They're asking you to find the value of T when x = 1/3, so you all need to do is replace x by its value (in this case by 1/3) in the equation.

T = 3x + 2
T = 3 * (1/3) + 2
T = 3/3 + 2
T = 1 + 2
T = 3

So when x = 1/3 , T = 3.

Hope this Helps! :D
3 0
3 years ago
Read 2 more answers
-5x+y=-3
serg [7]
(3)(-5x+y=-3)
(5)(3x-8y=24)

-15x+3y=-9
15x-40y=120

3y=-9
-40y=120

-37y=111
Divide both sides by -37

y=-3

To solve for x. Choose one equation from the given and plug what you get in Y.

I'll choose, -5x+y=-3
So, -5x+(-3)=-3
-5x=0
Divide both sides by -5
x=0/-5

Hope, this helps.
5 0
3 years ago
Evaluate 2x2 - 1 when x = 3.
tigry1 [53]
X should equal 11
2(3)2-1
6(2)-1
12-1
11
6 0
3 years ago
Read 2 more answers
Helpppppp me right now!
Rudik [331]

Answer:

B and D

7/12 cups

Step-by-step explanation:

2 1/3 + 2 1/4 = cups of flour needed

4 = cups of flour had

2 1/3 + 2 1/4

To have the same denominator, we take the lcm

2 + 2 + (4/12 + 3/12) =

2 4/12 + 2 3/12 - 4

Or

2 + 2 + (3 + 4) / 12 - 4

2 + 2 + (3 + 4) / 12 - 4 = 4 7/12 - 4

4 7/12 - 4 = 7/12 cups of flour needed

8 0
3 years ago
Other questions:
  • Use a special triangle on the unit circle to determine the value of tan π/6.
    5·1 answer
  • The ymca lap pool is a right rectangular prism 36.8\, \text{m}36.8m36, point, 8, space, m long by 20 \,\text{m}20m20, space, m w
    11·2 answers
  • Find the price per unit for each item, then choose the best buy. a. Cereal, 10 oz. box for $5.90 would b. Cereal, 24 oz. box for
    8·2 answers
  • 87+100<br> What is 90 divided by 10
    11·2 answers
  • Convert 0.000002954 to scientific notation.
    13·2 answers
  • A flight from New York City to Chicago takes 3 1/2 hours
    12·1 answer
  • It is 3:27 pm in 24 hours it will be what time
    14·2 answers
  • How to solve -(y+-6)=-1
    6·1 answer
  • 3.
    11·1 answer
  • Help will mark Brainliest​
    12·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!