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3 years ago

How many 3-digit number can you write with only 4 and 7?

Mathematics

1 answer:

Jlenok [28]3 years ago

7 0

Answer:

8 numbers

Step-by-step explanation:

447

477

474

774

744

747

777

444

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Assume that X is a binomial random variable with n = 27 and p = 0.90. Calculate the following probabilities. (Do not round inter

Yuki888 [10]

Answer:

a) $P(X=26) = 27C26 (0.9)^{26} (1-0.9)^{27-26}= 0.1744$

b) $P(X=25) = 27C25 (0.9)^{25} (1-0.9)^{27-25}= 0.2520$

c) $P(X=25) = 27C25 (0.9)^{25} (1-0.9)^{27-25}= 0.2520$

$P(X=26) = 27C26 (0.9)^{26} (1-0.9)^{27-26}= 0.1744$

$P(X=27) = 27C27 (0.9)^{27} (1-0.9)^{27-27}= 0.0582$

And addind the values we got:

$P(X\geq 25)= P(X=25)+P(X=26)+P(X=27)=0.2520+0.1744+0.0582=0.4846$

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:

$X \sim Binom(n=27, p=0.9)$

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:

$P(X=26)$

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

$P(X=26) = 27C26 (0.9)^{26} (1-0.9)^{27-26}= 0.1744$

Part b

We want this probability:

$P(X=25)$

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

$P(X=25) = 27C25 (0.9)^{25} (1-0.9)^{27-25}= 0.2520$

Part c

We want this probability:

$P(X\geq 25)= P(X=25)+P(X=26)+P(X=27)$

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

$P(X=25) = 27C25 (0.9)^{25} (1-0.9)^{27-25}= 0.2520$

$P(X=26) = 27C26 (0.9)^{26} (1-0.9)^{27-26}= 0.1744$

$P(X=27) = 27C27 (0.9)^{27} (1-0.9)^{27-27}= 0.0582$

And addind the values we got:

$P(X\geq 25)= P(X=25)+P(X=26)+P(X=27)=0.2520+0.1744+0.0582=0.4846$

3 0

4 years ago

How many models of 100 do you need to model 3,200

atroni [7]

32 models of 100. you are prone for elementary questions in all subjects and i accept that very dearly, thank you

5 0

4 years ago

Read 2 more answers

(x+7)(x+4) what is the answer

zaharov [31]

Your answer is 2x+28

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4 years ago

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Can anyone help? 25 points

N76 [4]

Answer:

A) 85x=5865

x=69 Width

B)2(57)+2x=286

114+2x=286

2x=172

x=86

Step-by-step explanation:

3 0

3 years ago

Someone help please (worth 50 points!!)

padilas [110]

Answer:
1. 10^2
2. 10^4
3. 10^5
4. 10^7
5. 10^6
6. 10^3
7. 10^9
8. 10^0

9. 1000
10. 100,000
11. 10
12. 1,000,000
13. 100
14. 10
15. 10,000
16. 10,000,000

6 0

3 years ago