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3 years ago

Solve the system for the value of x and y

Mathematics

1 answer:

horrorfan [7]3 years ago

3 0

What is the system that you have to solve to find the value of x and y?

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3 years ago

A local hardware store sold 12 percent of its hammers on Saturday . If the hardware store sold 9 hammers on Saturday how many ha

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$\frac{12}{100}$ = $\frac{9}{x}$ Cross multiply

12x=900 Divide both sides by 12.

x=75 hammers to begin with.

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3 years ago

Help me please? Thanks!

love history [14]

Answer:

It's C

Step-by-step explanation:

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3 years ago

A new medical test provides a false positive result for hepatitis 2% of the time that is a perfectly healthy subject being teste

Oxana [17]

Given that X be the number of subjects who test positive for the disease out of the 30 healthy subjects used for the test.

The probability of success, i.e. the probability that a healthy subject tests positive is given as 2% = 0.02

Part A:

The probability that all 30 subjects will appropriately test as not being infected, that is the probability that none of the healthy subjects will test positive is given by:

 $P(X)={ ^nC_xp^x(1-p)^{n-x}} \\ \\ P(0)={ ^{30}C_0(0.02)^0(1-0.02)^{30-0}} \\ \\ =1(1)(0.98)^{30}=0.5455$


Part B:

The mean of a binomial distribution is given by

 $\mu=np \\ \\ =30(0.02) \\ \\ =0.6$

The standard deviation is given by:

 $\sigma=\sqrt{np(1-p)} \\ \\ =\sqrt{30(0.02)(1-0.02)} \\ \\ =\sqrt{30(0.02)(0.98)}=\sqrt{0.588} \\ \\ =0.7668$


Part C:

This test will not be a trusted test in the field of medicine as it has a standard deviation higher than the mean. The testing method will not be consistent in determining the infection of hepatitis.

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3 years ago

A person recently read that 84% of cat owners are women. How large a sample should the researcher take if she wishes to be 90% c

Lana71 [14]

Answer:

405

Step-by-step explanation:

To find sample size, use the following equation, where n = sample size, za/2 = the critical value, p = probability of success, q = probability of failure, and E = margin of error.

$n=\frac{(z_{\frac{\alpha }{2} })^{2} *p*q }{E^2}$

The values that are given are p = 0.84 and E = 0.03.

You can solve for the critical value which is equal to the z-score of (1 - confidence level)/2. Use the calculator function of invNorm to find the z-score. The value will given with a negative sign, but you can ignore that.

(1 - 0.9) = 0.1/2 = 0.05

invNorm(0.05, 0, 1) = 1.645

You can also solve for q which is 1 - p. For this problem q = 1 - 0.84 = 0.16

Plug the values into the equation and solve for n.

$n =\frac{(1.645)^2*0.84*0.16}{(0.03)^2}\\n= 404.0997333$

Round up to the next number, giving you 405.

6 0

3 years ago