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
ohaa [14]
3 years ago
10

A particular telephone number is used to receive both voice calls and fax messages. Suppose that 25% of the incoming calls invol

ve fax messages, and consider a sample of 25 incoming calls. (Round your answers to three decimal places.)
Required:
a. What is the probability that at most 4 of the calls involve a fax message?
b. What is the probability that exactly 4 of the calls involve a fax message?
c. What is the probability that at least 4 of the calls involve a fax message?
d. What is the probability that more than 4 of the calls involve a fax message?
Mathematics
1 answer:
bagirrra123 [75]3 years ago
8 0

Answer:

a) 0.214 = 21.4% probability that at most 4 of the calls involve a fax message

b) 0.118 = 11.8% probability that exactly 4 of the calls involve a fax message

c) 0.904 = 90.4% probability that at least 4 of the calls involve a fax message

d) 0.786 = 78.6% probability that more than 4 of the calls involve a fax message

Step-by-step explanation:

For each call, there are only two possible outcomes. Either it involves a fax message, or it does not. The probability of a call involving a fax message is independent of other calls. So we use the binomial probability distribution to solve this question.

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}.p^{x}.(1-p)^{n-x}

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

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

And p is the probability of X happening.

25% of the incoming calls involve fax messages

This means that p = 0.25

25 incoming calls.

This means that n = 25

a. What is the probability that at most 4 of the calls involve a fax message?

P(X \leq 4) = P(X = 0) + P(X = 1) + P(X = 2) + P(X = 3) + P(X = 4).

In which

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

P(X = 0) = C_{25,0}.(0.25)^{0}.(0.75)^{25} = 0.001

P(X = 1) = C_{25,1}.(0.25)^{1}.(0.75)^{24} = 0.006

P(X = 2) = C_{25,2}.(0.25)^{2}.(0.75)^{23} = 0.025

P(X = 3) = C_{25,3}.(0.25)^{3}.(0.75)^{22} = 0.064

P(X = 4) = C_{25,4}.(0.25)^{4}.(0.75)^{21} = 0.118

P(X \leq 4) = P(X = 0) + P(X = 1) + P(X = 2) + P(X = 3) + P(X = 4) = 0.001 + 0.006 + 0.025 + 0.064 + 0.118 = 0.214

0.214 = 21.4% probability that at most 4 of the calls involve a fax message

b. What is the probability that exactly 4 of the calls involve a fax message?

P(X = 4) = C_{25,4}.(0.25)^{4}.(0.75)^{21} = 0.118

0.118 = 11.8% probability that exactly 4 of the calls involve a fax message.

c. What is the probability that at least 4 of the calls involve a fax message?

Either less than 4 calls involve fax messages, or at least 4 do. The sum of the probabilities of these events is 1. So

P(X < 4) + P(X \geq 4) = 1

We want P(X \geq 4). Then

P(X \geq 4) = 1 - P(X < 4)

In which

P(X < 4) = P(X = 0) + P(X = 1) + P(X = 2) + P(X = 3)

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

P(X = 0) = C_{25,0}.(0.25)^{0}.(0.75)^{25} = 0.001

P(X = 1) = C_{25,1}.(0.25)^{1}.(0.75)^{24} = 0.006

P(X = 2) = C_{25,2}.(0.25)^{2}.(0.75)^{23} = 0.025

P(X = 3) = C_{25,3}.(0.25)^{3}.(0.75)^{22} = 0.064

P(X

P(X \geq 4) = 1 - P(X < 4) = 1 - 0.096 = 0.904

0.904 = 90.4% probability that at least 4 of the calls involve a fax message.

d. What is the probability that more than 4 of the calls involve a fax message?

Very similar to c.

P(X \leq 4) + P(X > 4) = 1

From a), P(X \leq 4) = 0.214)

Then

P(X > 4) = 1 - 0.214 = 0.786

0.786 = 78.6% probability that more than 4 of the calls involve a fax message

You might be interested in
Max was on vacation twice as long as Jared and half as longas Wesley. The boys were on vacation a total of 3 weeks. How many day
lord [1]
Make an equation.
Also, convert 3 weeks into days ⇒ 3 · 7 = 21 days.

x + 2x + 4x = 21

x is Jared.
2x is Max (because half of 4 is 2).
4x is Wesley.

Now solve the equation.

7x = 21
x = 3

Jared = x
Max = 2x
Wesley = 4x

Jared = 3 days
Max = 2(3) = 6 days
Wesley = 4(3) = 12 days
4 0
3 years ago
Reduce the fraction:<br> 7b-14b²/42b²21b
ch4aika [34]

Answer:

(1-2b)/126b^2

Step-by-step explanation:

(7b-14b^2)/(42b^2*21b)

factor out the 7b,

[7b(1-2b)]/882b^3

[7b(1-2b)]/[7b(126b^2)]

cancel out the 7b's

(1-2b)/126b^2

7 0
3 years ago
Identify the constant of proportionality from the table.
ivann1987 [24]

Answer:

The constant of proportionality is 3.

Step-by-step explanation:

6/2 is 3 and so on.

Correct me if I'm wrong

3 0
2 years ago
WHY IS THIS GETTING DELETED?? I NEED HELP
aliina [53]

If this exact question is repeatedly deleted, it's probably because of the ambiguity of the given equation. I see two likely interpretations, for instance:

\dfrac{(5\times5)^k}{5^{-8}} = 5^3

or

\dfrac{5\times 5^k}{5^{-8}} = 5^3

If the first one is what you intended, then

\dfrac{(5\times5)^k}{5^{-8}} = \dfrac{(5^2)^k}{5^{-8}} = \dfrac{5^{2k}}{5^{-8}} = 5^{2k-(-8)} = 5^{2k+8} = 5^3

and it follows that

2<em>k</em> + 8 = 3   ==>   2<em>k</em> = -5   ==>   <em>k</em> = -5/2

If you meant the second one, then

\dfrac{5\times 5^k}{5^{-8}} = \dfrac{5^1\times5^k}{5^{-8}} = \dfrac{5^{k+1}}{5^{-8}} = 5^{k+1-(-8)} = 5^{k+9} = 5^3

which would give

<em>k</em> + 9 = 3   ==>   <em>k</em> = -6

And for all I know, you might have meant some other alternative... When you can, you should include a picture of your problem.

3 0
3 years ago
The ratio of sweaters to dresses that Jennifer has is 8:5. If
melomori [17]

Answer:

Ratio of sweaters to dresses = 8 : 5

Sum of ratios = 13

Let number of sweater + dresses = x

number \ of \ sweaters = \frac{8}{13} *x\\\\24 = \frac{8}{13}*x\\\\x = \frac{24*13}{8} = 3*13 = 39

number \ of \ dresses = 39 - 24 = 15

8 0
3 years ago
Other questions:
  • What is an easier way to solve algebraic expressions?
    6·1 answer
  • Describe what is meant by the statement “Renting can restrict ones lifestyle.”
    12·1 answer
  • A sample of 300 FM residents was taken and 135 said their favorite season was summer. Calculate a 99% confidence interval for th
    8·2 answers
  • How to solve 7(x+2y)=
    7·1 answer
  • Can someone identify the alternate interior angle? Please refer to image below.
    14·2 answers
  • If g(x) = -2x5 - 4, find g(2).
    5·1 answer
  • If a jogger travelledat the speed of 8km/h for 15mins how far did she run
    9·1 answer
  • Pls answer asap 7 - 3 r = r - 4 ( 2 + r)​
    15·1 answer
  • Which of the following
    14·1 answer
  • Need help with angle solving​
    10·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!