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Zarrin [17]
3 years ago
13

A vaccine has 90% probability of being effective in preventing a certain disease. the probability of getting the disease if the

person is not vaccinated is 50%. in certain geographic region, 25% of the people get vaccinated. if a person is selected at random , find the probability that he or she will contract the disease
Mathematics
1 answer:
IgorLugansk [536]3 years ago
4 0
If 25% of the people <em>are</em> vaccinated, then 75% of the people are <em>not</em> vaccinated.  Of those not vaccinated, each has a 50% chance of contracting the disease.  The probability that someone is both not vaccinated and contracts the disease is (0.75)(0.5)=0.375.
The probability that someone is vaccinated and contracts the disease is (0.25)(0.1)=0.025 (it is multiplied by 0.1 because if the vaccine is 90% effective, then there is a 10% chance someone that is vaccinated can contract the disease.
Add these together for the total:  0.375+0.025=0.4
There is a 40% chance that someone chosen at random will contract the disease.
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The summer monsoon brings 80% of India's rainfall and is essential for the country's agriculture.
Natasha_Volkova [10]

Answer:

Step 1. Between 688 and 1016mm. Step 2. Less than 688mm.

Step-by-step explanation:

The <em>68-95-99.7 rule </em>roughly states that in a <em>normal distribution</em> 68%, 95% and 99.7% of the values lie within one, two and three standard deviation(s) around the mean. The z-scores <em>represent values from the mean</em> in a <em>standard normal distribution</em>, and they are transformed values from which we can obtain any probability for any normal distribution. This transformation is as follows:

\\ z = \frac{x - \mu}{\sigma} (1)

\\ \mu\;is\;the\;population\;mean

\\ \sigma\;is\;the\;population\;standard\;deviation

And <em>x</em> is any value which can be transformed to a z-value.

Then, z = 1 and z = -1 represent values for <em>one standard deviation</em> above and below the mean, respectively; values of z = 2 and z =-2, represent values for two standard deviations above and below the mean, respectively and so on.

Because of the 68-95-99.7 rule, we know that approximately 95% of the values for a normal distribution lie between z = -2 and z = 2, that is, two standard deviations below and above the mean as remarked before.

<h3>Step 1: Between what values do the monsoon rains fall in 95% of all years?</h3>

Having all this information above and using equation (1):

\\ z = \frac{x - \mu}{\sigma}  

For z = -2:

\\ -2 = \frac{x - 852}{82}

\\ -2*82 + 852 = x

\\ x_{below} = 688mm

For z = 2:

\\ 2 = \frac{x - 852}{82}

\\ 2*82 = x - 852

\\ 2*82 + 852 = x

\\ x_{above} = 1016mm

Thus, the values for the monsoon rains fall between 688mm and 1016mm for approximately 95% of all years.

<h3>Step 2: How small are the monsoon rains in the driest 2.5% of all years?</h3>

The <em>driest of all years</em> means those with small monsoon rains compare to those with high values for precipitations. The smallest values are below the mean and at the left part of the normal distribution.

As you can see, in the previous question we found that about 95% of the values are between 688mm and 1016mm. The rest of the values represent 5% of the total area of the normal distribution. But, since the normal distribution is <em>symmetrical</em>, one half of the 5% (2.5%) of the remaining values are below the mean, and the other half of the 5% (2.5%) of the remaining values are above the mean. Those represent the smallest 2.5% and the greatest 2.5% values for the normally distributed data corresponding to the monsoon rains.

As a consequence, the value <em>x </em>for the smallest 2.5% of the data is precisely the same at z = -2 (a distance of two standard deviations from the mean), since the symmetry of the normal distribution permits that from the remaining 5%, half of them lie below the mean and the other half above the mean (as we explained in the previous paragraph). We already know that this value is <em>x</em> = 688mm and the smallest monsoons rains of all year are <em>less than this value of x = </em><em>688mm</em>, representing the smallest 2.5% of values of the normally distributed data.

The graph below shows these values. The shaded area are 95% of the values, and below 688mm lie the 2.5% of the smallest values.

3 0
3 years ago
The bulletin board is in the shape of a square. Find two rational numbers that are within 1/8 in of the actualy side length.
Pachacha [2.7K]
16 because it iscvbnmvcxcvbnmvcxcvbnm,
7 0
3 years ago
Read 2 more answers
Of the students who eat in a certain cafeteria, each student either likes or dislikes lima beans and each student either likes o
spayn [35]

Answer: There are 32 students who like brussels sprouts but dislike beans.

Step-by-step explanation:

Since we have given that

Number of students eat in the cafeteria = 120

Fraction dislike lime beans = \dfrac{2}{3}

Fraction who dislike lime beans and brussles sprouts both = \dfrac{2}{3}\times \dfrac{3}{5}

Fraction who dislikes lime beans but not brussles is given by

\dfrac{2}{3}(1-\dfrac{3}{5})\\\\=\dfrac{2}{3}\times \dfrac{2}{5}\\\\=\dfrac{4}{15}

So, Number of students who like brussels sprouts but dislike lima beans is given by

\dfrac{4}{15}\times 120\\\\=32

Hence, there are 32 students who like brussels sprouts but dislike beans.

7 0
3 years ago
He length of a rectangle is three times its width. The perimeter of the rectangle is at most 112 cm.
g100num [7]
The equation relating length to width
L = 3W
The inequality stating the boundaries of the perimeter
LW <= 112
When you plug in what L equals in the first equation into the second equation, you get
3W * W <= 112
evaluate
3W^2 <= 112
3W <= 4 \sqrt{7}
W <= \frac{4 \sqrt{7} }{3} cm
8 0
3 years ago
Read 2 more answers
What is the domain of f(x)=9-x²<br> A(.fx)≥9<br> B.All real numbers<br> C.-3≤x≤3<br> D. x≤9
Ber [7]

Answer:

B. all real numbers

Step-by-step explanation:

hope that helps

3 0
3 years ago
Read 2 more answers
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