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defon
2 years ago
15

Suppose that in a population of 1000 there are 300 defective items and 700 items that are not defective. if you are selecting tw

o items at random from this population, what is the probability they will both be defective?
Mathematics
1 answer:
natulia [17]2 years ago
4 0
This is a combinations problem.

The total number of possible 2-item combinations is (1000 choose 2)

The number of 2-defective combinations is (300 choose 2)

The probability = \frac{300 C 2}{1000 C 2} = 0.09
You might be interested in
The sales manager of a company awarded a total of \$3000$3000 in bonuses to the most productive salespeople. The bonuses were aw
alisha [4.7K]

Answer:

one possible number of bonus is 9.

Step-by-step explanation:

Let, the number of $250 bonus = x and number of $750 bonus = y.

We have that bonuses are given in amounts $250 and $750.

Since, the total bonus is $3000.

So, we get,

250x + 750y = 3000.

As, there is atleast one $250 bonus and atleast one $750 bonus.

Let, the minimum number of bonus of $750 be 1 i.e. y = 1.

Substitute in the equation gives,

250x + 750 × 1 = 3000

i.e. 250x = 3000 - 750

i.e. 250x = 2250

i.e. x = 9

Thus, the maximum number of $250 bonus are 9.

Hence, one possible number of bonus is 9.

4 0
2 years ago
George tells you that when variables are in the denominator, the equation four over five plus three over x equals one over two b
jeka57 [31]
<span><span><u>Answer</u>
This explanation shows that the equation is solvable and there is not where in the steps we get a zero on the denominator.


</span><span><u>Explanation</u>
</span><span>The equation given in the statement is;
4/5+3/x=1/2
This equation can be solved as follows:
4/5+3/x=1/2
3/x=1/2-4/5=(5-8)/10
3/x= -3/10
Taking the reciprocal on both side of the equation;
x/3=-10/3
Multiplying by 3 both sides we get;
</span><span>x= -10
</span></span>
3 0
2 years ago
Read 2 more answers
A set of data has a mean of 56.1. The data follows a normal distribution curve and has a standard deviation of 8.2. Find the pro
Whitepunk [10]
Given that mean=56.1 and standard deviation=8.2, P(x>67.5) will be found as follows:
The z-score is given by:
z=(x-μ)/σ
thus the z-score will be given by:
z=(67.5-56.1)/8.2
z=11.4/8.2
z=1.39
thus
P(z=1.39)=0.9177
thus:
P(x>67.5)=1-P(z>0.9177)
=1-0.9177
=0.0823
Answer: A. 0.0823
7 0
2 years ago
Read 2 more answers
I need to find both of the solutions to the equation 100+(n-2)^ = 149
rodikova [14]

Answer:

Step-by-step explanation:

hello :

100+(n-2)² = 149

100-100+(n-2)² = 149-100

(n-2)² = 49  

(n-2)² - 49  =0    but 49=7²

(n-2)² - 7²  =0   use identity : a²-b²=(a-b)(a+b)

(n-2-7)(n-2+7)=0

(n-9)(n+5)=0

n-9=0 or n+5=0

n=9 or n=-5

                                             

5 0
2 years ago
The manufacturer of hardness testing equipment uses steel-ball indenters to penetrate metal that is being tested, however, the m
masha68 [24]

Answer:

1.667-2.31\frac{1.803}{\sqrt{9}}=0.2789  

1.667+2.31\frac{1.803}{\sqrt{9}}=3.055  

So on this case the 95% confidence interval would be given by (0.2789;3.055)  

The 95% confidence interval to judge whether the two indeners result in different measurements is?

Yes the confidence interval not contains the value 0 so we can conclude that the values for Diamond are significantly higher than the values for Steel Ball at 5% of significance.

Step-by-step explanation:

We have the following dataset:

specimen    1     2    3     4      5     6     7    8     9

Steel Ball   51   57   61   70   68   54   65  51   53

Diamond   53   55  63   74   69   56   68  51   56

If we calculate the differences diamond-steel ball we have this datase:

d: 2, -2, 2, 4, 1, 2, 3, 0, 3

The second step is calculate the mean difference  

\bar d= \frac{\sum_{i=1}^n d_i}{n}=1.667

The third step would be calculate the standard deviation for the differences, and we got:

s_d =\frac{\sum_{i=1}^n (d_i -\bar d)^2}{n-1} =1.803

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".  

The margin of error is the range of values below and above the sample statistic in a confidence interval.  

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".  

The confidence interval for the mean is given by the following formula:  

\bar X \pm t_{\alpha/2}\frac{s}{\sqrt{n}} (1)  

In order to calculate the critical value t_{\alpha/2} we need to find first the degrees of freedom, given by:  

df=n-1=9-1=8  

Since the confidence is 0.95 or 95%, the value of \alpha=0.05 and \alpha/2 =0.025, and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-T.INV(0.025,9)".And we see that t_{\alpha/2}=2.31.

Now we have everything in order to replace into formula (1):  

1.667-2.31\frac{1.803}{\sqrt{9}}=0.2789  

1.667+2.31\frac{1.803}{\sqrt{9}}=3.055  

So on this case the 95% confidence interval would be given by (0.2789;3.055)  

The 95% confidence interval to judge whether the two indeners result in different measurements is?

Yes the confidence interval not contains the value 0 so we can conclude that the values for Diamond are significantly higher than the values for Steel Ball at 5% of significance.

4 0
2 years ago
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