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Anna11 [10]
4 years ago
13

A box contains two defective Christmas tree lights that have been inadvertently mixed with eight nondefective lights. If the lig

hts are selected one at a time without replacement and tested until both defective lights are found, what is the probability that both defective lights will be found after exactly three trials? (Round your answer to four decimal places.)
Mathematics
1 answer:
REY [17]4 years ago
6 0
Possibility 1: nondefective-defective-defective
possibility 2: defective-nondefective-defective

possibility 1: 8/10x 2/9 x 1/8 = 16/720=1/45
possibility 2: 2/10 x 8/9 x 1/8= 16/720=1/45

answer: 2/45
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Several years​ ago, 38​% of parents who had children in grades​ K-12 were satisfied with the quality of education the students r
Colt1911 [192]

Answer:

0.428 - 1.96\sqrt{\frac{0.428(1-0.428)}{1165}}=0.3995

0.428 + 1.96\sqrt{\frac{0.428(1-0.428)}{1165}}=0.4564

We are confident that the true proportion of people satisfied with the quality of education the students receive is between (0.3995, 0.4564), since the lower value for this confidence level is higher than 0.38 we have enough evidence to conclude that the parents' attitudes toward the quality of education have changed.

Step-by-step explanation:

For this case we are interesting in the parameter of the true proportion of people satisfied with the quality of education the students receive

The confidence level is given 95%, the significance level would be given by \alpha=1-0.95=0.05 and \alpha/2 =0.025. And the critical values are:

z_{\alpha/2}=-1.96, z_{1-\alpha/2}=1.96

The estimated proportion of people satisfied with the quality of education the students receive is given by:

\hat p =\frac{499}{1165}= 0.428

The confidence interval for the proportion if interest is given by the following formula:  

\hat p \pm z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}

And replacing the info given we got:

0.428 - 1.96\sqrt{\frac{0.428(1-0.428)}{1165}}=0.3995

0.428 + 1.96\sqrt{\frac{0.428(1-0.428)}{1165}}=0.4564

We are confident that the true proportion of people satisfied with the quality of education the students receive is between (0.3995, 0.4564), since the lower value for this confidence level is higher than 0.38 we have enough evidence to conclude that the parents' attitudes toward the quality of education have changed.

8 0
4 years ago
55% of 6th grade students voted in the student election. 440 sixth grade students voted in the student election. How many total
Ne4ueva [31]

Answer:

800. Here's why:

Step-by-step explanation:

This indicats that 440 students make up 55% of the 6th grade population. We can write this as

55/440.

We also know that 'x' total students make up 100% of the 6th-grade population, so we can write this as

100/x.

55/440 must be equal to 100/x. When cross multiplied, it becomes 50x=44000. If we divided each side by 50, we'll find that x=880. Therefore, there are 800 6th graders

8 0
3 years ago
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Vertex formula = -b/2a
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B) (12,0) (6,0)
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4 years ago
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What is 4 and square root of 72
Katarina [22]

Answer:

square root of 72 is approximately 8.49

i hope that right!

Step-by-step explanation:

8 0
3 years ago
Xavier wants to distribute his baseball card collection evenly among his 8 younger brothers. What equation can be used to find c
defon
This would be D:).... C = the number of cards his brothers each get. 

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