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STALIN [3.7K]
1 year ago
11

Question 9 20% of a particular brand of light bulbs fail in one year. What is the probability that three bulbs out of a random c

ollection of 8 bulbs fail in one year
Mathematics
1 answer:
Delvig [45]1 year ago
5 0

Answer:

The correct answer is 0.15

Step-by-step explanation:

According to the given scenario, the probability is as follows:

X\sim Bin (n,p)

Here

n = 8

p = 0.20 or 20%

Now this is a binomial probability distribution

P(X) = ^nC_x \times p^x \tmes (1 - p)^{n-x}\\\\P(3) = ^8C_3 \tims 0.20^3 \times (1 - 0.20)^5

= 0.15

Hence, the correct answer is 0.15

You might be interested in
A newly hired basketball coach promised a high-paced attack that will put more points on the board than the team’s previously te
puteri [66]

Answer:

a. z = 2.00

Step-by-step explanation:

Hello!

The study variable is "Points per game of a high school team"

The hypothesis is that the average score per game is greater than before, so the parameter to test is the population mean (μ)

The hypothesis is:

H₀: μ ≤ 99

H₁: μ > 99

α: 0.01

There is no information about the variable distribution, I'll apply the Central Limit Theorem and approximate the sample mean (X[bar]) to normal since whether you use a Z or t-test, you need your variable to be at least approximately normal. Considering the sample size (n=36) I'd rather use a Z-test than a t-test.

The statistic value under the null hypothesis is:

Z= X[bar] - μ  = 101 - 99 = 2

σ/√n 6/√36

I don't have σ, but since this is an approximation I can use the value of S instead.

I hope it helps!

7 0
2 years ago
A sample of bacteria is growing at a rate of 8% per hour compound continuously. How many hours will it take for the sample to do
Anettt [7]

Answer:

The sample would double in 9 hours

Step-by-step explanation

The number of hours it will take for the sample to double can be found using the 72 rule.

The 72 rule is such that a growth rate would double itself by it is used in dividing the number 72 as shown below:

number of hours =72/8=9 hours

The number of hours it would take the sample to double is 9 hours as computed above.

6 0
2 years ago
if Amanda hikes at an average speed of 2.72 miles per hour, how long will it take her to hike 6.8 miles
kompoz [17]
Speed times time=distance
distance=6.8
speed=2.72
time=?

2.72 times ?=6.8
divide both sides by 2.72
?=2.5

answer si 2.5 hours
3 0
2 years ago
Read 2 more answers
A member of a student team playing an interactive marketing game received the fol- lowing computer output when studying the rela
nirvana33 [79]

Answer:

p_v = 2*P(t_{n-2} > |t_{calc}|)= 0.91

So on this case for the significance level assumed \alpha=0.05 we see that p_v >\alpha so then we can conclude that the result is NOT significant. And we don't have enough evidence to reject the null hypothesis.

So on this case is not appropiate say that :"the more we spend on advertising this product, the fewer units we sell" since the slope for this case is not significant.

Step-by-step explanation:

Let's suppose that we have the following linear model:

y= \beta_o +\beta_1 X

Where Y is the dependent variable and X the independent variable. \beta_0 represent the intercept and \beta_1 the slope.  

In order to estimate the coefficients \beta_0 ,\beta_1 we can use least squares procedure.  

If we are interested in analyze if we have a significant relationship between the dependent and the independent variable we can use the following system of hypothesis:

Null Hypothesis: \beta_1 = 0

Alternative hypothesis: \beta_1 \neq 0

Or in other words we want to check is our slope is significant (X have an effect in the Y variable )

In order to conduct this test we are assuming the following conditions:

a) We have linear relationship between Y and X

b) We have the same probability distribution for the variable Y with the same deviation for each value of the independent variable

c) We assume that the Y values are independent and the distribution of Y is normal  

The significance level assumed on this case is \alpha=0.05

The standard error for the slope is given by this formula:

SE_{\beta_1}=\frac{\sqrt{\frac{\sum (y_i -\hat y_i)^2}{n-2}}}{\sqrt{\sum (X_i -\bar X)^2}}

Th degrees of freedom for a linear regression is given by df=n-2 since we need to estimate the value for the slope and the intercept.  

In order to test the hypothesis the statistic is given by:

t=\frac{\hat \beta_1}{SE_{\beta_1}}

The p value on this case would be given by:

p_v = 2*P(t_{n-2} > |t_{calc}|)= 0.91

So on this case for the significance level assumed \alpha=0.05 we see that p_v >\alpha so then we can conclude that the result is NOT significant. And we don't have enough evidence to reject the null hypothesis.

So on this case is not appropiate say that :"the more we spend on advertising this product, the fewer units we sell" since the slope for this case is not significant.

3 0
2 years ago
A started some business with RS 26,000. After 3 month B joined him with Rs. 16,000. After some more time C joined them with Rs.
viktelen [127]

Answer:

3  months

Step-by-step explanation:

<h2><u>A:</u></h2>

We know that the total investment period is 1 year, then since A started, A invested Rs 26,000.

<u>Now, since A has been working for 12 months, this is where the effective investment comes in:</u>

A effective investment = Rs 312,000

<h2><u>B:</u></h2>

<u>Then after 3 months, B joined, so:</u>

12 months - 3 months = 9 months in work

B overall invested = Rs 16,000

<u>Since B only worked nine months, we use that to find effective investment:</u>

B effective investment = Rs 144,000

<h2>C:</h2>

<u>C joined x months since B joined in:</u>

<u>We don't know how much C worked for, but we know that C joined after B:</u>

C investment period = 9 months - x certain amount of months

We know that C's investment is Rs 25,000

<u>Find effective investment:</u>

<u>Rs 25,000 * ( 9 - x ) = Rs 225,000 - 25,000x then to find the total investment:</u>

<u></u>

<u>Add all effective investment:</u>

Rs 312,000 + Rs 144,000 + Rs 225,000 - 25,000x

= Rs 681000 - 25,000x

We now know that C's investment is 225,000 - 25,000x

<u>Find profit share:</u> 225,000 - 25,000x

==> Rs 3,825

<u>The total profit:</u>

Rs 15,453

<u>To get our final answer, we must do this operation:</u>

<u>C investment divided by Total Investment = C's profit and total profit:</u>

( Rs 225,000 - 25,000x) ÷ ( Rs 681,000 - 25,000x ) = Rs 3,825 / Rs 15,453

25 ( Rs 9,000 - 1,000x)/(Rs 681,000 - 25,000x)  = (153 * 25) /(153 * 101)

( Rs 9,000 - 1,000x ) ÷ ( Rs 681,000 - 25,000x ) = 1 / 101

Rs 909,000 - 101,000x = Rs 681,000 - 25,000x

Rs 228,000 = 76,000x

Rs 228 = 76x

x = 3

8 0
2 years ago
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