Ask question

Ask question

All categories

3 years ago

11

John wants to nail a thumbtack on his circular board, pictured below. If the thumbtack is equally likely to be placed anywhere o

n the board, what is the probability that the thumbtack will be placed on the inner circle? Use 3.14 for , and round your answer to the nearest whole percent. A. 51% B. 55% C. 57% D. 60%

1 answer:

yulyashka [42]3 years ago

3 0

Answer:

$Probability = 51\%$

Step-by-step explanation:

Given

Radius of inner circle = 5ft

Radius of outer circle = 7ft

Required

Determine the probability that the thumbtack will be placed on the inner circle

We start by calculating the area of both circles;

Inner Circle

$Area = \pi r^2$

$Area = 3.14 * 5^2$

$Area = 3.14 * 25$

$Area = 78.5$

Outer Circle

$Area = \pi R^2$

$Area = 3.14 * 7^2$

$Area = 3.14 * 49$

$Area = 153.86$

At this point, the probability can be calculated;

The probability = Area of Inner Circle / Area of Outer Circle

$Probability = \frac{78.5}{153.86}$

$Probability = 0.51020408163$

Convert to percentage

$Probability = 0.51020408163 * 100\%$

$Probability = 51.020408163\%$

Approximate

$Probability = 51\%$

You might be interested in

A student wants to construct the inscribed circle of a triangle. What is the first step she should take?

Leviafan [203]

D) construction of the angle bisector.
So if you have a triangle that is not equilateral the perpendicular bisectors would not work so you need angle bisectors.
I have drawn a diagram
The green is the angle bisectors and the yellow the perpendicular bisectors.
You can see the problem straight away

4 0

2 years ago

Read 2 more answers

Wht is 39% of 1,200? I can't understand it

Gennadij [26K]

Something percent of a number must be smaller than the number.
And also, 39% of a number is equal to 39/100 multiplied by the number.

Thus:
39/100 * 1200
39/1 * 12
468

8 0

3 years ago

Read 2 more answers

Let the number of chocolate chips in a certain type of cookie have a Poisson distribution. We want the probability that a cookie

ludmilkaskok [199]

Answer:

$\lambda \geq 6.63835$

Step-by-step explanation:

The Poisson Distribution is "a discrete probability distribution that expresses the probability of a given number of events occurring in a fixed interval of time or space if these events occur with a known constant mean rate and independently of the time since the last event".

Let X the random variable that represent the number of chocolate chips in a certain type of cookie. We know that $X \sim Poisson(\lambda)$

The probability mass function for the random variable is given by:

$f(x)=\frac{e^{-\lambda} \lambda^x}{x!} , x=0,1,2,3,4,...$

And f(x)=0 for other case.

For this distribution the expected value is the same parameter $\lambda$

$E(X)=\mu =\lambda$

On this case we are interested on the probability of having at least two chocolate chips, and using the complement rule we have this:

$P(X\geq 2)=1-P(X$

Using the pmf we can find the individual probabilities like this:

$P(X=0)=\frac{e^{-\lambda} \lambda^0}{0!}=e^{-\lambda}$

$P(X=1)=\frac{e^{-\lambda} \lambda^1}{1!}=\lambda e^{-\lambda}$

And replacing we have this:

$P(X\geq 2)=1-[P(X=0)+P(X=1)]=1-[e^{-\lambda} +\lambda e^{-\lambda}[]$

$P(X\geq 2)=1-e^{-\lambda}(1+\lambda)$

And we want this probability that at least of 99%, so we can set upt the following inequality:

$P(X\geq 2)=1-e^{-\lambda}(1+\lambda)\geq 0.99$

And now we can solve for $\lambda$

$0.01 \geq e^{-\lambda}(1+\lambda)$

Applying natural log on both sides we have:

$ln(0.01) \geq ln(e^{-\lambda}+ln(1+\lambda)$

$ln(0.01) \geq -\lambda+ln(1+\lambda)$

$\lambda-ln(1+\lambda)+ln(0.01) \geq 0$

Thats a no linear equation but if we use a numerical method like the Newthon raphson Method or the Jacobi method we find a good point of estimate for the solution.

Using the Newthon Raphson method, we apply this formula:

$x_{n+1}=x_n -\frac{f(x_n)}{f'(x_n)}$

Where :

$f(x_n)=\lambda -ln(1+\lambda)+ln(0.01)$

$f'(x_n)=1-\frac{1}{1+\lambda}$

Iterating as shown on the figure attached we find a final solution given by:

$\lambda \geq 6.63835$

4 0

2 years ago

Can someone please help me

Aneli [31]

Answer:

r = 5

Step-by-step explanation:

To solve for r, plug in the change in x values and change in y values, since the hypotenuse is simply the diagonal of both the y-coordinate and x-coordinates shown via drawing legs on the vertical and horizontal axis. So, since (0,0) is the initial point, r = sqr[(-4-0)^2 + (-3-0)^2 = sqr(16 + 9) = 5.

Now, the angle theta is the angle in which the sine, cosine, and tangent ratios are found. Simply use opposite over hypotenuse for sine, adjacent over hypotenuse for cosine, and opposite over adjacent for tangent using theta as the angle in which these values are obtained.

5 0

2 years ago

On a number line what are the missing values between 5.1 and 5.2

daser333 [38]

Answer:

Anything from 5.11 to 5.19 can be the missing values.

4 0

3 years ago