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SCORPION-xisa [38]
3 years ago
5

Thuy rolls a number cube 7 times. which expression represents the probability of rolling a 4 exactly 2 times?

Mathematics
2 answers:
Nady [450]3 years ago
6 0
The result of rolling a number cube 7 times is a 7-digit number composed of digits 1,2,3,4,5 and 6 so that digits can repeat. The total number of possibilities is 6^7.

The number of possibilities where 4 appears exactly two times is 5^5*(7!-6!/2).
 5^5 is the number of 5-digits numbers composed of digits 1,2,3,5 and 6 so that digits can repeat.
7! is the number of permutations of digits 1,2,3,4,4,5 and 6.
6! is the number of permutations of digits 1,2,3,{4,4},5 and 6.
We don't want to subtract all numbers where digits 4 appear side by side. That's why we must divide 6! by 2.

Finally, the probability is P=5^5(7!-6!/2)/7^7
mel-nik [20]3 years ago
5 0

Answer:

The answer is C I just took the test!!!!!!!

Step-by-step explanation:


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A sequence of Bernoulli trials consists of choosing components at random from a batch of components. A selected component is eit
Drupady [299]

Answer:

a) 0.0287 = 2.87% probability that three non-defective components in a batch of seven components.

b) 0.0336 = 3.36% probability that 8 non-defective components are drawn before the first defective component is chosen.

Step-by-step explanation:

A sequence of Bernoulli trials composes the binomial distribution.

Binomial probability distribution

The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.

P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}

In which C_{n,x} is the number of different combinations of x objects from a set of n elements, given by the following formula.

C_{n,x} = \frac{n!}{x!(n-x)!}

And p is the probability of X happening.

The probability that a selected component is non-defective is 0.8

This means that p = 0.8

a) Three non-defective components in a batch of seven components.

This is P(X = 3) when n = 7. So

P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}

P(X = 3) = C_{7,3}.(0.8)^{3}.(0.2)^{4} = 0.0287

0.0287 = 2.87% probability that three non-defective components in a batch of seven components.

b) 8 non-defective components are drawn before the first defective component is chosen.

Now the order is important, so the we just multiply the probabilities.

8 non-defective, each with probability 0.8, and then a defective, with probability 0.2. So

p = (0.8)^8*0.2 = 0.0336

0.0336 = 3.36% probability that 8 non-defective components are drawn before the first defective component is chosen.

4 0
3 years ago
I need someone to solve this problem for me please
Amiraneli [1.4K]
First, solve the area of the entire large rectangle (28)(45) = 1260
Next, find the area of the chunk that is cut out (11)(15) = 165
- we know the width is 15 because 45 - 6 - 24
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7 0
3 years ago
Read 2 more answers
I need to know the answer asap
Doss [256]

subtract lowest time from highest time for each kind

129-29 = 100

320-210 = 110

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7 0
3 years ago
A man is listening to his radio at the top of a mountain where the altitude is 4500 feet
AURORKA [14]
But what say it again wit what is this
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Add the following complex numbers: (5-3i)+(10+5i)
serious [3.7K]

Answer:

i = 7.5

Step-by-step explanation:

(5-3i)+(10+5i)

(5+10)+(5i-3i)

15+2i

15=-2i

15/2-i

7.5=i

6 0
3 years ago
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