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
harkovskaia [24]
3 years ago
9

Eight swimmers participate in a race in how many ways can the swimmers finish in first second and third place an it be answered

using combinations or permutations
Mathematics
1 answer:
Vesnalui [34]3 years ago
3 0

Answer:

336

Step-by-step explanation:

To define whether we use permutations or combinations we must define whether or not the order in which we arrange the results matters. If the order matters we use permutations and if the order doesn't matter we use combinations.

In this case, since we are talking about the first places in a competition, order definitely does matter, so we use permutations. Also in permutations it must be indicated if repetition is allowed, in this case not because the same person cannot be in more than one place.

We use the following formula:

P=\frac{n!}{(n-r)!}

where in this case n is the numer of swimmers and r is the number of places we are considering (1st 2nd and 3rd), which is 3 places.

n = 8

and

r = 3

thus the number of permutations is given bt:

P=\frac{8!}{(8-3)!}\\ \\P=\frac{8!}{5!} \\\\P=\frac{8*7*6*5*4*3*2*1}{5*4*3*2*1}\\ \\P=8*7*6\\P=336

the answer is that there are 336 ways in which the swimmers can finish in first second and third place

You might be interested in
The life of a red bulb used in a traffic signal can be modeled using an exponential distribution with an average life of 24 mont
BartSMP [9]

Answer:

See steps below

Step-by-step explanation:

Let X be the random variable that measures the lifespan of a bulb.

If the random variable X is exponentially distributed and X has an average value of 24 month, then its probability density function is

\bf f(x)=\frac{1}{24}e^{-x/24}\;(x\geq 0)

and its cumulative distribution function (CDF) is

\bf P(X\leq t)=\int_{0}^{t} f(x)dx=1-e^{-t/24}

• What is probability that the red bulb will need to be replaced at the first inspection?

The probability that the bulb fails the first year is

\bf P(X\leq 12)=1-e^{-12/24}=1-e^{-0.5}=0.39347

• If the bulb is in good condition at the end of 18 months, what is the probability that the bulb will be in good condition at the end of 24 months?

Let A and B be the events,

A = “The bulb will last at least 24 months”

B = “The bulb will last at least 18 months”

We want to find P(A | B).

By definition P(A | B) = P(A∩B)P(B)

but B⊂A, so  A∩B = B and  

\bf P(A | B) = P(B)P(B) = (P(B))^2

We have  

\bf P(B)=P(X>18)=1-P(X\leq 18)=1-(1-e^{-18/24})=e^{-3/4}=0.47237

hence,

\bf P(A | B)=(P(B))^2=(0.47237)^2=0.22313

• If the signal has six red bulbs, what is the probability that at least one of them needs replacement at the first inspection? Assume distribution of lifetime of each bulb is independent

If the distribution of lifetime of each bulb is independent, then we have here a binomial distribution of six trials with probability of “success” (one bulb needs replacement at the first inspection) p = 0.39347

Now the probability that exactly k bulbs need replacement is

\bf \binom{6}{k}(0.39347)^k(1-0.39347)^{6-k}

<em>Probability that at least one of them needs replacement at the first inspection = 1- probability that none of them needs replacement at the first inspection. </em>

This means that,

<em>Probability that at least one of them needs replacement at the first inspection =  </em>

\bf 1-\binom{6}{0}(0.39347)^0(1-0.39347)^{6}=1-(0.60653)^6=0.95021

5 0
3 years ago
(3.2 + 6.8)x - (36 divided by 4)x PLEASE HELPPP
Mrac [35]

Answer:

i dont no but what i got was 10x+144d^3 but do u want to sovle for x i got u X

Step-by-step explanation:

6 0
3 years ago
Solve the system by elimination.(show your work)
PilotLPTM [1.2K]

Answer:

x = 1 , y = 1 , z = 0

Step-by-step explanation by elimination:

Solve the following system:

{-2 x + 2 y + 3 z = 0 | (equation 1)

-2 x - y + z = -3 | (equation 2)

2 x + 3 y + 3 z = 5 | (equation 3)

Subtract equation 1 from equation 2:

{-(2 x) + 2 y + 3 z = 0 | (equation 1)

0 x - 3 y - 2 z = -3 | (equation 2)

2 x + 3 y + 3 z = 5 | (equation 3)

Multiply equation 2 by -1:

{-(2 x) + 2 y + 3 z = 0 | (equation 1)

0 x+3 y + 2 z = 3 | (equation 2)

2 x + 3 y + 3 z = 5 | (equation 3)

Add equation 1 to equation 3:

{-(2 x) + 2 y + 3 z = 0 | (equation 1)

0 x+3 y + 2 z = 3 | (equation 2)

0 x+5 y + 6 z = 5 | (equation 3)

Swap equation 2 with equation 3:

{-(2 x) + 2 y + 3 z = 0 | (equation 1)

0 x+5 y + 6 z = 5 | (equation 2)

0 x+3 y + 2 z = 3 | (equation 3)

Subtract 3/5 × (equation 2) from equation 3:

{-(2 x) + 2 y + 3 z = 0 | (equation 1)

0 x+5 y + 6 z = 5 | (equation 2)

0 x+0 y - (8 z)/5 = 0 | (equation 3)

Multiply equation 3 by 5/8:

{-(2 x) + 2 y + 3 z = 0 | (equation 1)

0 x+5 y + 6 z = 5 | (equation 2)

0 x+0 y - z = 0 | (equation 3)

Multiply equation 3 by -1:

{-(2 x) + 2 y + 3 z = 0 | (equation 1)

0 x+5 y + 6 z = 5 | (equation 2)

0 x+0 y+z = 0 | (equation 3)

Subtract 6 × (equation 3) from equation 2:

{-(2 x) + 2 y + 3 z = 0 | (equation 1)

0 x+5 y+0 z = 5 | (equation 2)

0 x+0 y+z = 0 | (equation 3)

Divide equation 2 by 5:

{-(2 x) + 2 y + 3 z = 0 | (equation 1)

0 x+y+0 z = 1 | (equation 2)

0 x+0 y+z = 0 | (equation 3)

Subtract 2 × (equation 2) from equation 1:

{-(2 x) + 0 y+3 z = -2 | (equation 1)

0 x+y+0 z = 1 | (equation 2)

0 x+0 y+z = 0 | (equation 3)

Subtract 3 × (equation 3) from equation 1:

{-(2 x)+0 y+0 z = -2 | (equation 1)

0 x+y+0 z = 1 | (equation 2)

0 x+0 y+z = 0 | (equation 3)

Divide equation 1 by -2:

{x+0 y+0 z = 1 | (equation 1)

0 x+y+0 z = 1 | (equation 2)

0 x+0 y+z = 0 | (equation 3)

Collect results:

Answer: {x = 1 , y = 1 , z = 0

6 0
3 years ago
Read 2 more answers
The number of chairs increased by 7 <br><br> A.cx7<br> B.c+7<br> C.c/7<br> D.c-7
miss Akunina [59]
B.c+7
hope that helps!
7 0
3 years ago
10. A perfect circle measuring 38 feet across was discovered on Brickell Avenue in Miami in 1998. Known as the Miami Circle at B
vivado [14]

Using an exponential function, it is found that the Tequesta settlement is 1845 years old.

<h3>What is an exponential function?</h3>

The exponential equation for a decaying amount of a substance is given by:

A(t) = A(0)e^{-rt}

In which:

  • A(0) is the initial value.
  • r is the decay rate, as a decimal.

Researching on the internet, the half-life of carbon 14 is of 5,730 years, hence A(5730) = 0.5A(0), which we use to find r.

A(t) = A(0)e^{-rt}

0.5A(0) = A(0)e^{-5730r}

e^{-5730r} = 0.5

\ln{e^{-5730r}} = \ln{0.5}

5730r = -\ln{0.5}

r = -\frac{\ln{0.5}}{5730}

r = 0.00012096809

Hence, the equation is:

A(t) = A(0)e^{-0.00012096809t}

The wood chips were found to contain 80% of the atmospheric carbon-14, hence we have to find t for which A(t) = 0.8A(0).

A(t) = A(0)e^{-0.00012096809t}

0.8A(0) = A(0)e^{-0.00012096809t}

e^{-0.00012096809t} = 0.8

\ln{e^{-0.00012096809t}} = \ln{0.8}

-0.00012096809t = \ln{0.8}

t = -\frac{\ln{0.8}}{0.00012096809}

t = 1845

The Tequesta settlement is 1845 years old.

You can learn more about exponential functions at brainly.com/question/25537936

8 0
2 years ago
Other questions:
  • PLS HELP IM DESPARATE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
    7·2 answers
  • Find the product or quotient. Express using positive exponents
    13·1 answer
  • Explain how you would find the sign of the quotient of 32 divided by -2 over -16 divided by 4
    8·1 answer
  • A light shines from the top of a pole 50ft high. a ball is dropped from the same height from a point 30 ft away from the light.
    13·1 answer
  • 270 divided by 17 need help
    6·2 answers
  • PLEASE HELP!!!
    5·2 answers
  • Someone please help me. ASAP
    14·1 answer
  • 2 5/6 times 8 as a mixed number.
    14·1 answer
  • 18-3×5+32÷4 (show with procedure fast..)​
    10·2 answers
  • I NEED HELP!! THIS MY FINAL!
    13·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!