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3 years ago

Help! I’ll mark brainlest :(

Mathematics

1 answer:

disa [49]3 years ago

7 0

Answer:

I'm guessing its b, but I'm not too sure

Step-by-step explanation:

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Awarding BRAINLIEST! Please help!!

MariettaO [177]

The correct answer is -1/3.

8 0

3 years ago

Read 2 more answers

A university found that 20% of its students withdraw without completing the introductory statistics course. Assume that 20 stude

EleoNora [17]

Answer:

a) $P(X \leq 2)= P(X=0)+P(X=1)+P(X=2)$

And we can use the probability mass function and we got:

$P(X=0)=(20C0)(0.2)^0 (1-0.2)^{20-0}=0.0115$

$P(X=1)=(20C1)(0.2)^1 (1-0.2)^{20-1}=0.0576$

$P(X=2)=(20C2)(0.2)^2 (1-0.2)^{20-2}=0.1369$

And adding we got:

$P(X \leq 2)=0.0115+0.0576+0.1369 = 0.2061$

b) $P(X=4)=(20C4)(0.2)^4 (1-0.2)^{20-4}=0.2182$

c) $P(X>3) = 1-P(X \leq 3) = 1- [P(X=0)+P(X=1)+P(X=2)+P(X=3)]$

$P(X=0)=(20C0)(0.2)^0 (1-0.2)^{20-0}=0.0115$

$P(X=1)=(20C1)(0.2)^1 (1-0.2)^{20-1}=0.0576$

$P(X=2)=(20C2)(0.2)^2 (1-0.2)^{20-2}=0.1369$

$P(X=3)=(20C3)(0.2)^3 (1-0.2)^{20-3}=0.2054$

And replacing we got:

$P(X>3) = 1-[0.0115+0.0576+0.1369+0.2054]= 1-0.4114= 0.5886$

d) $E(X) = 20*0.2= 4$

Step-by-step explanation:

Previous concepts

The binomial distribution is a "DISCRETE probability distribution that summarizes the probability that a value will take one of two independent values under a given set of parameters. The assumptions for the binomial distribution are that there is only one outcome for each trial, each trial has the same probability of success, and each trial is mutually exclusive, or independent of each other".

Solution to the problem

Let X the random variable of interest, on this case we now that:

$X \sim Binom(n=20, p=0.2)$

The probability mass function for the Binomial distribution is given as:

$P(X)=(nCx)(p)^x (1-p)^{n-x}$

Where (nCx) means combinatory and it's given by this formula:

$nCx=\frac{n!}{(n-x)! x!}$

Part a

We want this probability:

$P(X \leq 2)= P(X=0)+P(X=1)+P(X=2)$

And we can use the probability mass function and we got:

$P(X=0)=(20C0)(0.2)^0 (1-0.2)^{20-0}=0.0115$

$P(X=1)=(20C1)(0.2)^1 (1-0.2)^{20-1}=0.0576$

$P(X=2)=(20C2)(0.2)^2 (1-0.2)^{20-2}=0.1369$

And adding we got:

$P(X \leq 2)=0.0115+0.0576+0.1369 = 0.2061$

Part b

We want this probability:

$P(X=4)$

And using the probability mass function we got:

$P(X=4)=(20C4)(0.2)^4 (1-0.2)^{20-4}=0.2182$

Part c

We want this probability:

$P(X>3)$

We can use the complement rule and we got:

$P(X>3) = 1-P(X \leq 3) = 1- [P(X=0)+P(X=1)+P(X=2)+P(X=3)]$

$P(X=0)=(20C0)(0.2)^0 (1-0.2)^{20-0}=0.0115$

$P(X=1)=(20C1)(0.2)^1 (1-0.2)^{20-1}=0.0576$

$P(X=2)=(20C2)(0.2)^2 (1-0.2)^{20-2}=0.1369$

$P(X=3)=(20C3)(0.2)^3 (1-0.2)^{20-3}=0.2054$

And replacing we got:

$P(X>3) = 1-[0.0115+0.0576+0.1369+0.2054]= 1-0.4114= 0.5886$

Part d

The expected value is given by:

$E(X) = np$

And replacing we got:

$E(X) = 20*0.2= 4$

3 0

3 years ago

Will give brainliest for *BEST* answer!

Nataliya [291]

Use substitution and substitute y into the other equation. One of the equations already gives you y in terms of x, so use that and substitute it into the other equation. y = 3x - 4

Plug into the other equation: -3y = -9x + 12
-3(3x-4) = -9x + 12
-9x + 12 = -9x + 12
This is an identity. So that means that any value of x makes this equation true. So B.

8 0

3 years ago

3x-2y=6 thats The Problem I Need Help On

Roman55 [17]

Solve for Y?

Subtract -3x.
Then didvidd by -2 to get Y by itself.

Y= 3/2y -3

X-Intercept: (2,0)
Y-Intercept: (0,-3)

6 0

3 years ago

Disk requests come in to the disk driver for cylinders 10, 22, 20, 2, 40, 6, and 38, in that order. A seek takes 6 msec per cyli

m_a_m_a [10]

Answer:

a) 876 ms

b) 360 ms

c) 348 ms

Step-by-step explanation:

a) When using the First-come, first serve order, the starts at the initial cylinder and is served in the same order as it arrives.

For First-come, first serve, the order is served from (20), 10, 22, 20, 2, 40, 6, and 38.

Seek time = 10 + 12 + 2+ 18 + 38 + 34 + 32 = 146 cylinder

The request uses 146 cylinders, therefore the seek time = 146 cylinder * 6 ms/cylinder = 876 ms

b) When using the Closest cylinder next the request starts at the initial cylinder and is served using the shortest movement from current position.

For Elevator algorithm, the order is served from (20), 20, 22, 10, 6, 2, 38, 40

Seek time = 0 + 2 + 12+ 4 + 4 + 36 + 2 = 60 cylinder

The request uses 146 cylinders, therefore the seek time = 60 cylinder * 6 ms/cylinder = 360 ms

c) When using the Elevator algorithm the request starts at the initial cylinder and moves upwards, then reverses direction.

For Closest cylinder next, the order is served from (20), 20, 22, 38, 40, 10, 6, 2

Seek time = 0 + 2 + 16+ 2 + 30 + 4 + 4 = 58 cylinder

The request uses 146 cylinders, therefore the seek time = 58 cylinder * 6 ms/cylinder = 348 msa) When using the First-come, first serve order, the starts at the initial cylinder and is served in the same order as it arrives.

For First-come, first serve, the order is served from (20), 10, 22, 20, 2, 40, 6, and 38.

Seek time = 10 + 12 + 2+ 18 + 38 + 34 + 32 = 146 cylinder

The request uses 146 cylinders, therefore the seek time = 146 cylinder * 6 ms/cylinder = 876 ms

b) When using the Closest cylinder next the request starts at the initial cylinder and is served using the shortest movement from current position.

For Elevator algorithm, the order is served from (20), 20, 22, 10, 6, 2, 38, 40

Seek time = 0 + 2 + 12+ 4 + 4 + 36 + 2 = 60 cylinder

The request uses 146 cylinders, therefore the seek time = 60 cylinder * 6 ms/cylinder = 360 ms

c) When using the Elevator algorithm the request starts at the initial cylinder and moves upwards, then reverses direction.

For Closest cylinder next, the order is served from (20), 20, 22, 38, 40, 10, 6, 2

Seek time = 0 + 2 + 16+ 2 + 30 + 4 + 4 = 58 cylinder

The request uses 146 cylinders, therefore the seek time = 58 cylinder * 6 ms/cylinder = 348 ms

3 0

3 years ago