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3 years ago

11

the scale of a tower to its scale model is 1 meter 5cm . if the tower is 6 meters by 20 meters what are the dimensions of the sc

ale model?

1 answer:

nikklg [1K]3 years ago

8 0

1 m = 5 cm

6 m = 6 * 5 = 30 cm
20 m = 20 * 5 = 100 cm

dimensions are : 30 cm by 100 cm

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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

PLZ HELP WILL GIVE BRAINLIEST

Naddik [55]

y = -0.65 (6) + 7.34

y = 3.44

but the dot plot showed when x = 6, y = 4

so 4 - 3.44 = 0.56

Answer

0.56

3 0

3 years ago

If three people are chosen at random, what is the probability that they were born in September?

Andrews [41]

1/4 becuase 3 out of 12 is rounded

8 0

3 years ago

Read 2 more answers

Sample methods that embody random sampling are often termed probability sampling methods. OTrue False

stepan [7]

Answer:

The answer is true.

Step-by-step explanation:

Sample methods that embody random sampling are often termed probability sampling methods.

Yes this is a true statement.

Random sampling means picking up the samples randomly from a whole population with each sample having an equal chance of getting selected.

For example- selecting randomly 10 students from each class of a school, to survey for the food quality in school's cafeteria.

And this is a type of probability sampling methods. Other types are stratified sampling, cluster sampling etc.

3 0

3 years ago

Mark invests $4200 in two different accounts. The first account paid 3 %, the second account paid 7 % in interest. At the end of

nexus9112 [7]

Answer:

3% interest account = $2,700

7% interest account = $1,500

Step-by-step explanation:

We have to use equation to find the answer. Again, we are using simple interest to find how much is in each account.

We know, Interest = Capital x Interest rate x year

Let,

3% interest account = X

7% interest account = Y

According to the question,

X*0.03*1 + Y*0.07*1 = 186 ................. (i)

Again, X + Y = 4200 .................. (ii)

From equation (Ii), we get,

or X = 4,200 - Y ...................... (iii)

Putting the value of X in equation (i), we can get,

(4,200 - Y)*0.03*1 + Y*0.07*1 = 186

or, 126 - 0.03Y + 0.07Y = 186

or, 0.04Y = 186-126

or, 0.04Y = 60

or, Y = 1,500

Putting Y = 1,500 in equation (iii), we get

X = 4,200 - 1,500

X = 2,700

Therefore, 3% account had $2,700 balance

7% account had $1,500 balance.

8 0

2 years ago