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Yuliya22 [10]
3 years ago
10

What is the value of x?2367​

Mathematics
1 answer:
Alex777 [14]3 years ago
4 0

Answer:

x = 2

Step-by-step explanation:

Using the property of two secants segments to a circle, we have that:

EB * EA = EC * ED

(x + 1)(x + 1 + 11) = (x + 4)(x + 4 + 1)

(x + 1)(x + 12) = (x + 4)(x + 5)

x^2 + 13x + 12 = x^2 + 9x + 20

13x + 12 =9x + 20

13x - 9x = 20 - 12

4x  = 8

x = 2

So the value of x is 2

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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
The numbers of boys and girls in each of the four classes of a high school are shown in the bar graph.
sattari [20]
To know for sure I’d need to see the bar graph. But with in the information present the answer would be 12.25% or 1/8
4 0
3 years ago
Read 2 more answers
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notka56 [123]

The solution is X=10.

8 0
3 years ago
Mr. Scruggs got some money for his birthday. He spent 1/5 of it on dog treats. Then, he divided the remainder equally among his
Mariulka [41]

Answer:

a. \frac{4a}{15}

b. $225

Step-by-step explanation:

Let Mr. Scruggs got money for his birthday be 'a'

He spent \frac{1}{5} of it on dog treats = a × \frac{1}{5}

                                                                      = \frac{1}{5}a

remainder amount would be = a - \frac{1}{5}a

                                                = \frac{4a}{5}

Then he divided the remainder money equally among 3 favorite charities.

\frac{\frac{4a}{5}}{3}

= \frac{4a}{15}

a. Each charity receive \frac{4a}{15}

b. If he donated $60 to each charity.

\frac{4a}{15}=60

a=\frac{15\times 60}{4}

a = $225

Mr. Scruggs received $225 for his birthday.

6 0
3 years ago
Lisa had 1750 stamps. Mark had 480 fewer stamps than Lisa. Lisa gave some stamps to Mark. Now Mark has three times as many stamp
FrozenT [24]
L: 1750, M:1750-480=1270
Lisa gave some stamps to Mark so Lisa now has 1750-x and Mark has 1270+x. Mark also has 3 times as many as Lisa now: (1750-x)*3=1270+x
5250-3*x=1270+x
4*x=3980, x=3980/4, x=995
So Lisa gave 995 stamps to Mark.
At first Mark had 1270 stamps. Lisa now has 1750-995=755 stamps.
7 0
2 years ago
Read 2 more answers
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