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Strike441 [17]
3 years ago
14

A financial talk show host claims to have a 55.3 % success rate in his investment recommendations. You collect some data over th

e next few weeks, and find that out 10 recommendations, he was correct 3 times. If the claim is correct and the performance of recommendations is independent, what is the probability that you would have observed 4 or fewer successfu
Mathematics
1 answer:
baherus [9]3 years ago
3 0

Answer:

There is a 25.52% probability of observating 4 our fewer succesful recommendations.

Step-by-step explanation:

For each recommendation, there are only two possible outcomes. Either it was a success, or it was a failure. So we use the binomial probability distribution to solve this problem.

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.

In this problem we have that:

p = 0.553, n = 10

If the claim is correct and the performance of recommendations is independent, what is the probability that you would have observed 4 or fewer successful:

This is

P(X \leq 4) = P(X = 0) + P(X = 1) + P(X = 2) + P(X = 3) + P(X = 4)

In which

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

P(X = 0) = C_{10,0}.(0.553)^{0}.(0.447)^{10} = 0.0003

P(X = 1) = C_{10,1}.(0.553)^{1}.(0.447)^{9} = 0.0039

P(X = 2) = C_{10,2}.(0.553)^{2}.(0.447)^{8} = 0.0219

P(X = 3) = C_{10,3}.(0.553)^{3}.(0.447)^{7} = 0.0724

P(X = 4) = C_{10,4}.(0.553)^{4}.(0.447)^{6} = 0.1567

P(X \leq 4) = P(X = 0) + P(X = 1) + P(X = 2) + P(X = 3) + P(X = 4) = 0.0003 + 0.0039 + 0.0219 + 0.0724 + 0.1567 = 0.2552

There is a 25.52% probability of observating 4 our fewer succesful recommendations.

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sveticcg [70]
Domain is the left and right values, which means any parabola opening up or down will have a domain of (-∞, ∞)
7 0
2 years ago
A manufacturer of Christmas light bulbs knows that 10% of these bulbs are defective. It is known that light bulbs are defective
andriy [413]

Answer:

(a) P(X \leq 20) = 0.9319

(b) Expected number of defective light bulbs = 15

(c) Standard deviation of defective light bulbs = 3.67

Step-by-step explanation:

We are given that a manufacturer of Christmas light bulbs knows that 10% of these bulbs are defective. It is known that light bulbs are defective independently. A box of 150 bulbs is selected at random.

Firstly, the above situation can be represented through binomial distribution, i.e.;

P(X=r) = \binom{n}{r} p^{r} (1-p)^{2} ;x=0,1,2,3,....

where, n = number of samples taken = 150

            r = number of success

           p = probability of success which in our question is % of bulbs that

                  are defective, i.e. 10%

<em>Now, we can't calculate the required probability using binomial distribution because here n is very large(n > 30), so we will convert this distribution into normal distribution using continuity correction.</em>

So, Let X = No. of defective bulbs in a box

<u>Mean of X</u>, \mu = n \times p = 150 \times 0.10 = 15

<u>Standard deviation of X</u>, \sigma = \sqrt{np(1-p)} = \sqrt{150 \times 0.10 \times (1-0.10)} = 3.7

So, X ~ N(\mu = 15, \sigma^{2} = 3.7^{2})

Now, the z score probability distribution is given by;

                Z = \frac{X-\mu}{\sigma} ~ N(0,1)

(a) Probability that this box will contain at most 20 defective light bulbs is given by = P(X \leq 20) = P(X < 20.5)  ---- using continuity correction

    P(X < 20.5) = P( \frac{X-\mu}{\sigma} < \frac{20.5-15}{3.7} ) = P(Z < 1.49) = 0.9319

(b) Expected number of defective light bulbs found in such boxes, on average is given by = E(X) = n \times p = 150 \times 0.10 = 15.

Standard deviation of defective light bulbs is given by = S.D. = \sqrt{np(1-p)} = \sqrt{150 \times 0.10 \times (1-0.10)} = 3.67

8 0
3 years ago
PLEASE HEP ME QUICK!!!!: Tom travels between the two mile markers shown and then finds his average speed in miles per hour. Sele
slega [8]

Answer:

speed=\frac{195\ miles}{3\ hours}

3\ hours=\frac{195\ miles}{speed}

3\ hours*(speed)=195\ miles

Step-by-step explanation:

we know that

The speed is equal to divide the distance by the time

Let

x -----> the distance in miles

y ----> the time in hours

speed=\frac{x}{y}

we have

The distance is equal to subtract 35 miles from 230 miles

x=230-35=195\ miles

The time is equal to subtract 1:30 pm from 4:30 pm

y=4:30\ pm-1:30\ pm=3\ hours

substitute in the formula of speed

speed=\frac{195\ miles}{3\ hours}

<em>Isolate 3 hours</em>

3\ hours=\frac{195\ miles}{speed}

<em>Isolate 195 miles</em>

195\ miles=3\ hours*(speed)

7 0
3 years ago
For pmalachi for answering my question
Nikolay [14]
I’m very confused lol.
5 0
2 years ago
What is 221,000,000,000,000,000,000 expressed in scientific notation?
Fiesta28 [93]
Your answer is g 2.21 x 1020
8 0
3 years ago
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