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3 years ago

Aron flips a penny 9 times. Which expression represents the probability of getting exactly 3 heads?

Mathematics

2 answers:

Sveta_85 [38]3 years ago

8 0

Answer:

Step-by-step explanation:

DedPeter [7]3 years ago

3 0

Answer:

$9C3*(0.5)^3(0.5)^6$

Step-by-step explanation:

The binomial probability formula shown has variables which represents:

n is the total number of trials (here, we flip penny 9 times, hence n = 9)

k is the number we want to find (here, we want the probability of 3 heads, so k = 3)

p is the probability of success (here, success means getting heads. So, in a coin flip the probability of heads is always 1/2, so p = 1/2)

<em>Putting all the info into the equation and using formula for nCk, we get:</em>

$P(k successes)=nCk*p^{k}(1-p)^{n-k}\\P(3Heads)=9C3*(0.5)^3(1-0.5)^{9-3}\\P(3Heads)=9C3*(0.5)^3(0.5)^6$

The first expression shown in the answer choices is right.

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An electrician cuts a 136 foot long piece of cable. One piece is 16 feet less than 3 times the length of the other piece. Find t

Ugo [173]

Answer:

98 ft and 38 ft

Step-by-step explanation:

We know that the initial length of the piece is 136 feet

Then the piece is cut into two pieces.

Let's call x the length of the first piece of cable and call z the length of the second piece of cable.

So we know that

$x + z = 136$

and

$x = 3z-16$

Now we substitute the second equation in the first one and solve for the variable z

$3z-16 + z = 136$

$4z-16= 136$

$4z= 136+16$

$z= \frac{152}{4}$

$z=38\ ft$

Now we find the length x

$x + 38 = 136$

$x= 136-38$

$x= 98\ ft$

7 0

4 years ago

Which describes the intersection of the plane and the solid?

alexandr1967 [171]

A hopefully it’s right

3 0

3 years ago

Read 2 more answers

The arm span and foot length were both measured (in centimeters) for each of 20 students in a biology class. The computer output

irina1246 [14]

Answer:

The guy above me is completely wrong hahaha.

The correct answer should have a 63%.

It's probably D. The terminology is a little confusing.

The equation of the output looks like:

-7.611 + .186(x) = y

x --> Arm span

y --> Foot span

The linear relationship is formed with the armspan.

6 0

3 years ago

Help please!!! Find the sum of the series show your work

AleksAgata [21]

Answer:

$\sum_{i=1}^{12}(3i-1) = 222$

Step-by-step explanation:

The given series is

$\sum_{i=1}^{12}(3i-1)$

The first term is

$f(1) = 3 \times 1 - 1 = 2$

The last term is

$f(12) = 3 \times 12 - 1 = 35$

To find the number of terms in the sequence, solve,

$3i - 1 = 35$

$3i = 36 \\ i = 12$

The sum of the first i-terms of an arithmetic sequence is:

$S_i = \frac{i}{2} (f(1) + f(2))$

We substitute the values to get;

$S_ {12}= \frac{12}{2} (2+ 35)$

$S_ {12}=6(37)$

$S_ {12}= 222$

6 0

4 years ago

A researcher wishes to estimate the percentage of adults who support abolishing the penny. What size sample should be obtained i

alex41 [277]

Answer:

sample size if he uses a previous estimate of 32% is 523

sample size if he does not use any prior estimates is 601

Step-by-step explanation:

estimate E = 4 percentage = 0.04

confidence Cl = 95% = 0.95

previous estimate p = 32% = 0.32

q = 1 - 0.32 = 0.68

to find out

size of sample

solution

first we calculate z value for 95% confidence E = 0.04 is 1.96

from probability P(-1.96 < z < 1.96) = 0.95)

here z = 1.96

so in 1st part size of sample we know

E = z × $\sqrt{pq/n}$

put all value E, z p and q and we get n

n = (z/E)² ×p×q

n = (1.96/0.04)² ×0.32×0.68

n = 523

sample size if he uses a previous estimate of 32% is 523

now in 2nd part we take p = 0.5

so n will be

n = (z/E)² ×p×q

n = (1.96/0.04)² ×0.5×0.5

n = 601

sample size if he does not use any prior estimates is 601

6 0

4 years ago