there are n counters in a bag. 4 of the counters are red and the rest are blue. Ross takes a counter from the bag at random and does not replace it. he then takes another counter at random from the bag. the probability Ross takes two blue counters is 1/3. find the value of n​

Answers

Answer 1

Answer: n = 10.

Step-by-step explanation:

In the bag, we have n counters.

4 of the counters are red.

the rest are blue, then we have:

(n - 4) blue counters.

Now, the probability that Ross takes a blue counter from the bag is equal to the quotient between the number of blue counters (n - 4) and the total number of counters, n

Then the probability is:

p1 = (n - 4)/n

Now he draws another, and it must be blue again, then we can calculate the probability in the same way as above, but he already take a blue counter, so the number of blue counters is (n - 5) and the total number of counters is (n - 1)

The probability of this event is:

p2 = (n - 5)/(n - 1)

The joint probability (the probability that Ross takes two blue counters) is equal to the product of the individual probabilities, and we know that this is equal to 1/3, then we have the equation:

1/3 = ( (n - 4)/n)*((n - 5)/(n - 1))

Now let's solve this for n.

n*(n - 1)/3 = (n - 4)*(n - 5)

(n^2 - n)/3 = n^2 - 4*n - 5*n + 20

n^2 - n = 3*(n^2 - 9*n + 20)

n^2 - n = 3*n^2 - 27*n + 60

0 = (3*n^2 - n^2) - 27*n + n + 60

0 = 2*n^2 - 26*n + 60

The two solutions of this equation can be found with Bhaskara's equation:

[tex]n = \frac{-(-26) +- \sqrt{(-26)^2 - 4*2*60} }{2*2} = \frac{26+- 14}{4}[/tex]

Then the two solutions are:

n = (26 - 14)/4 = 3

This is not an option, because we know for sure that we have 4 red counters, then this option can be discarded.

The other solution is:

n = (26 + 14)/4 = 40/4 = 10

Then we have n = 10, 10 counters in total.


Related Questions

1/3+1/4
IN FRACTION FORM

Answers

Answer:

7/12

Step-by-step explanation:

Plz mark brainliest :D

Answer:

7/12

Step-by-step explanation:

1

3

+

1

4

=

1

3

+

1

4

=

4

12

+

3

12

=

4+3

12

What is the value of x?

Answers

Answer:

16

Step-by-step explanation:

By the property of intersecting chords inside the circle, we have:

[tex](5x - 7) \degree = \frac{1}{2} (119 \degree + 27 \degree) \\ \\ (5x - 7) \degree = \frac{1}{2} \times 146 \degree\\ \\ (5x - 7) \degree = 73\degree \\ \\ 5x - 7 = 73 \\ \\ 5x = 73 + 7 \\ \\ 5x = 80 \\ \\ x = \frac{80}{5} \\ \\ x = 16[/tex]

Marcus paid 45 cents for 2 pencils. At that rate, what would 8 pencils cost? Ill give BRAINLIEST

Answers

Answer:

$1.8

Step-by-step explanation:

divide .45/2 and get .225

multiply this by 8 and get 1.8

it would cost 1.8n

Answer:

$1.80

Step-by-step explanation:

45/2 = 22.5 cents per pencil

0.225 × 8 = $1.8

I'm sorry please help.
Solve the following system of equations.
x-3y=17
x+7y=-23
x=
y=

Answers

Answer:

-4y=40

y=-10

x-3(-10)=17

x-30=17

x=17+30

x=47

Step-by-step explanation:

Answer:

x= 5

y= -4

Step-by-step explanation:

x= 17+3y so you substitute what you got for x in so

17 +3y +7y = -23

10y=-40

y=-4 now you put -4 in for y in the first equation

x = 17 + (3 times -4)

x = 17 - 12

x=5

what are the x and y intercepts for this equation y=−1/4x+2?
(_,_)

Answers

Answer:

(8, 0) is the x-intercept

(0, 2) is the y-intercept

Step-by-step explanation:

The y-intercept = 2 since the equation is in slope-intercept form.

The x-intercept occurs when y = 0

So,   0 = -1/4x + 2

        0 = -x + 8

         x = 8

(8, 0) is the x-intercept

(0, 2) is the y-intercept

What is the solution to the system of equations?

3x − 6y = −12
−x + 2y = 8

Answers

3x-6y=-12 the answer is -4+2y but u didn’t say solve for what so I solved for x
-x+2y=8 the answer is y= 4+x/2 but u didn’t say solve for what so I solve for y this time

Help ASAP thanks........

Answers

The answer is 130 degrees is the answer

Can someone help ASAP pls

Answers

Answer:

Step-by-step explanation:

first the answer is most definenetly 130 and 160 and i dont think its 30 so 50.

What is the M<1

21
42
71
82

Answers

Answer:

I think the answer is C. 71

Answer:

c

Step-by-step explanation:

edge 2025 trust rn

Please help asap please i give brainliest

Answers

Answer:

D.

Step-by-step explanation:

If wrong so sorry I am a bit rusty

c because it was exaclty reflected. pls give brainliest i really need it :/

Find the the value of x
I’ll mark the brainiest

Answers

Answer:

6

Step-by-step explanation:

What is 3 to the third power (4 + 4)

Answers

Answer:

216

Step-by-step explanation:

Answer:

(4+4)= 8 essa é resposta para mim mas não sê si esta certa

please help me find the solution ​

Answers

C.) (-4,3)
Use the process of elimination and plug in the answer of x or y to one of the problems

Q3.
Bill's weight decreases from 64.8 kg to 59.3 kg.
Calculate the percentage decrease in Bill's weight.
Give your answer correct to 3 significant figures.

Answers

Answer:

8.48%

Step-by-step explanation:

Bill's weight decreases from 64.8 kg to 59.3 kg.

We need to find the percentage decrease in Bill's weight. It can be calculated as follows :

[tex]\%=\dfrac{64.8 -59.3 }{64.8 }\times 100\\\\=8.48\%[/tex]

So, the required decrease in percentage is 8.48%.

What is the length of a diagonal of a rectangular picture whose sides are 12" x 17" round to the nearest 10th of an inch

Answers

a^2 + b^2 = c^2
12^2 + 17^2 = 485
so c^2=485
so c=22.0 inches

Plsssssss answer its due in 10 minutes , thxxx ! :c

Answers

Answer:

3x, -4, 2x, 6

Step-by-step explanation:

Key:

Red = negative
Long = variables
Green/Yellow = positive


1.) Three long greens = 3x

2.) 6 yellows = 6

3.) 4 red = -4

4.) 2 long reds = -2x


Hope it helped

The blue pen is 12 cm long the red pen is 72 mm long what is the difference between the 2 pens?

Answers

Answer:

the difference between the 2 pens is 4.8 cm

Charles purchases a car for $50,187 at 1.9% add-on rate for 6 years.

Answers

Answer:

good for him

Step-by-step explanation:

given cos A = 0.36, find angle A in degrees. round your answer to the nearest hundredth.

Answers

Answer:

68.9°

Step-by-step explanation:

[tex]cos^{-1}[/tex](0.36) ≈ 68.90

Find the zeros of f (x)
5.x2 + 35.
The zeros are
and

Answers

Answer:

5(x2+7)

Step-by-step explanation:

solve the system by graphing
y = x -1 y = -2x -4

Answers

Answer:

d = 26.196374

For:

(X1, Y1) = (-7, -4)

(X2, Y2) = (17, 6.5)

PLZ HELP I GIVE U BRAINLIEST

Answers

Answer:

Step-by-step explanation:

231/32

7 7/32

Answer:

7 7/32

Step-by-step explanation:

someone help on this please

Answers

Answer:

C, D, F

Step-by-step explanation:

Simply put your equations into a free graphing calculator such as

DESMOS

and it's quite simple!

hope this helps!!

10 POINTS HELP ASAP!!!

Answers

Answer:

I think it is -7

Step-by-step explanation:

I WILL GIVE 200 POINT TO WHOEVER GET RIGHT The price of Philip's favorite candy has been reduced by 15¢ per piece. Philip buys 14 pieces and spends $3.22. What is the regular price of each piece of candy? Enter your answer in the box.

Answers

Answer:

0.23 $

Step-by-step explanation:

Answer:

6.52

Step-by-step explanation:

Solve this equation: 2x = 5

Answers

Answer:

2.5

Step-by-step explanation:

2x = 5

x = 5/2 = 2.5

I hope im right!!

X = 5/2 or 2.5 that is the answer

WILL GIVE BRAINLIEST!
Consider the following.
a number increased by the total of the number and five

Answers

Answer:

n + (n+5)

Step-by-step explanation:

A number (N) increased (+) by the total of the number = (N+) and five (5)

What is the distance between the points (4, -8) and (10,8)?

Answers

Answer:

you can not find the distance between them

Step-by-step explanation:

there are no like numbers, if the problem was 4, -8 and 4, 8 i could solve it, so sorry

Answer: Believe you can and you're halfway there

Have a great day!

I don’t have the answer but I’m just spreading positivity.

No, really, I can't figure it out.

​ ​

Answers

mutiply -5 by 7

-35+9 ×[tex]\frac{5}{5}[/tex]

cancel the common factor of 5

-35+9×1

multiply 9 by 1

-35 + 9

add -35 and 9

- 26

simplify and find each side
angles are 45 45 90!
will mark brainiest!

Answers

Answer:

X = 4.47  Y = 8.94

Step-by-step explanation:

2[tex]\sqrt{5}[/tex]= 2.23606798

2.23606798 x 2 = 4.47213596

-------

4.47213596

4.47213596^2 + 4.47213596^2 = 8.94427192^2

8.94427192^2 = 80

Square root of 80 is 8.94

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