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BARSIC [14]
2 years ago
12

In this problem we will be dealing with the probability density function (pdf) associated with a continuous random variable, X.

Remember that the pdf is basically a function that assigns a probability density to the event of X taking a value x in the domain of X, with following two properties:
1 f(x) > 0, for all x
2 f(x) dx = 1.
f(x) does not give us the exact probability of X to take value x. Since the size of the domain of X is infinite, you cannot calculate the probability. Instead, you can calculate the probability of X to lie within a range:
Pr(a < X < b) = - / sa f(x) dx
Consider the following pdf function: 6x(1 – x) if 0 < x < 1,
f(x) = 0 otherwise. Calculate the probability of P(0.3 < X < 0.7)
a) 0.784
b) 0.568
c) 0.216
d) -0.568
Mathematics
1 answer:
konstantin123 [22]2 years ago
3 0

Answer:

b)\ 0.568

Step-by-step explanation:

Given

f(x) = 6x(1- x);\ 0 \le x \le 1

Required

P(0.3 < x < 0.7)

From the question, we have:

P(a < x < b) = \int\limits^b_a {f(x)} \, dx

So, we have:

P(0.3 < x < 0.7) = \int\limits^{0.7}_{0.3} {6x(1 - x)} \, dx

Open bracket

P(0.3 < x < 0.7) = \int\limits^{0.7}_{0.3} {6x - 6x^2} \, dx

Integrate

P(0.3 < x < 0.7) =  \frac{6x^2}{2} - \frac{6x^3}{3}}|\limits^{0.7}_{0.3}

P(0.3 < x < 0.7) =  3x^2 - 2x^3|\limits^{0.7}_{0.3}

Substitute 0.7 and 0.3 for x

P(0.3 < x < 0.7) =  (3*0.7^2 - 2*0.7^3) - (3*0.3^2 - 2*0.3^3)

Using a calculator, we have:

P(0.3 < x < 0.7) =  (0.784) - (0.216)

Remove brackets

P(0.3 < x < 0.7) =  0.784 - 0.216

P(0.3 < x < 0.7) =  0.568

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The circumference of a sphere was measured to be 76 cm with a possible error of 0.5 cm. (a) Use differentials to estimate the ma
andreev551 [17]

The maximum error in the calculated surface area is 24.19cm² and the relative error is 0.0132.

Given that the circumference of a sphere is 76cm and error is 0.5cm.

The formula of the surface area of a sphere is A=4πr².

Differentiate both sides with respect to r and get

dA÷dr=2×4πr

dA÷dr=8πr

dA=8πr×dr

The circumference of a sphere is C=2πr.

From above the find the value of r is

r=C÷(2π)

By using the error in circumference relation to error in radius by:

Differentiate both sides with respect to r as

dr÷dr=dC÷(2πdr)

1=dC÷(2πdr)

dr=dC÷(2π)

The maximum error in surface area is simplified as:

Substitute the value of dr in dA as

dA=8πr×(dC÷(2π))

Cancel π from both numerator and denominator and simplify it

dA=4rdC

Substitute the value of r=C÷(2π) in above and get

dA=4dC×(C÷2π)

dA=(2CdC)÷π

Here, C=76cm and dC=0.5cm.

Substitute this in above as

dA=(2×76×0.5)÷π

dA=76÷π

dA=24.19cm².

Find relative error as the relative error is between the value of the Area and the maximum error, therefore:

\begin{aligned}\frac{dA}{A}&=\frac{8\pi rdr}{4\pi r^2}\\ \frac{dA}{A}&=\frac{2dr}{r}\end

As above its found that r=C÷(2π) and r=dC÷(2π).

Substitute this in the above

\begin{aligned}\frac{dA}{A}&=\frac{\frac{2dC}{2\pi}}{\frac{C}{2\pi}}\\ &=\frac{2dC}{C}\\ &=\frac{2\times 0.5}{76}\\ &=0.0132\end

Hence, the maximum error in the calculated surface area with the circumference of a sphere was measured to be 76 cm with a possible error of 0.5 cm is 24.19cm² and the relative error is 0.0132.

Learn about relative error from here brainly.com/question/13106593

#SPJ4

3 0
2 years ago
Explain why 81 3/4 equals 27
professor190 [17]
81 to the 4th root is 3 and 3 cubed is 27.
8 0
3 years ago
Read 2 more answers
Hi,
lyudmila [28]

Here I have answered your question. Hope this helps. pls give brainliest if possible. tks. Have a nice day!!

3 0
3 years ago
Forty five percent of middle schools have a horse as a mascot. If there are 420 middle schools how many have a horse as a mascot
allochka39001 [22]
189
Because you have to turn it into a percentage in order to know how many per 1 percent. So multiply 420 by 100 and get 4.2 then you multiply it by 45 and you get 189 so 179 schools have a horse mascot
3 0
3 years ago
At first it increased by 25% and then decreased by 40%
Makovka662 [10]

Answer: 12%


Step-by-step explanation:

Let the original salary be Rs a


Salary after increase = a + 40% of a


= a + 40a/100


= 140a/100


= 14a/10


= 7a/ 5


Salary after Decrease = 7a/5 - 20% of 7a/5


= 7a/5 - 20× 7a / 100 × 5


= 7a/5 - 7a/25


= ( 35a - 7a) / 25


= 28a/25


Absolute increase = 28a/25 - a


= 3a/25


Percentage = 3a/25 ×100 / a


= 3 × 4


= 12%

4 0
3 years ago
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