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Blizzard [7]
3 years ago
12

There are four blood types, and not all are equally likely to be in blood banks. Records in a local blood bank show that, histor

ically, 49% of donations are type O blood, 27% are type A blood, 20% are type B blood, and 4% are type AB blood. The blood bank takes a random sample of 40 donations from the past month, and finds that 25 were type O, 10 were type A, 4 were type B, and 1 was type AB. The blood bank will run a chi-square test for goodness of fit to determine if the sample shows evidence that the distribution of blood types this month differs from the historical distribution. Are the conditions for such a test met
Mathematics
1 answer:
zvonat [6]3 years ago
3 0

Answer:

No, because all the expected frequencies must be higher than 5.

Step-by-step explanation:  

The chi-square test might be performed in those situations in which we need to know if a series of observations adjust or not to a theoretical function, such as the normal, Poisson, or binomial.

The chi-square test does not require the number of files to coincide with the number of columns in the table. It does not establish any restriction about the number of modalities per variable. However, the expected frequencies or counts should not be less than five.

In the exposed example, this unique rule is not accomplished, so the chi-square test can not be performed.  

 

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There is a book sale at the library. The price for each book is $4. Which expression can be used to show how much money the libr
kompoz [17]

Answer:

4x=289

Step-by-step explanation:

this expression could easily help find what the number is by 289/4

5 0
3 years ago
Which of these points are on a line that has a slope of -3?
Ira Lisetskai [31]
Simple....

using the formula \frac{ y_{1}- y_{2}  }{ x_{1}- x_{2}  } to find slope....

1.)  (9,2)(4,3)

\frac{2-3}{9-4}= -\frac{1}{5} (No)

2.)  (9,2)(3,4)

\frac{2-4}{9-3} = -\frac{2}{6} =- \frac{1}{3} (No)

3.)  (2,9)(3,4)

\frac{9-4}{2-3} = \frac{5}{-1} =-5 (No)

4.)  (2,9)(4,3)

\frac{9-3}{2-4} = \frac{6}{-2} =-3 (YES!)

Thus, your answer.
3 0
3 years ago
Four times the sum of a number and 15 is at least 120. Find all possible solutions for x
zloy xaker [14]
First translate the English phrase "Four times the sum of a number and 15 is at least 120" into a mathematical inequality.

"Four times..." means we're multiplying something by 4.

"... the sum of a number and 15..." means we're adding an unknown and 15 and then multiplying the result by 4.

"... is at least 120" means when we substitute the unknown for a value, in order for that value to be in the solution set, it can only be less than or equal to 120.

So, the resulting inequality is 4(x + 15) ≤ 120.

Simplify the inequality.

4(x + 15) ≤ 120
4x + 60 ≤ 120 <-- Using the distributive property
4x ≤ 60 <-- Subtract both sides by 60
x ≤ 15 <-- Divide both sides by 4

Now that we have the inequality in a simplified form, we can easily see that in order to be in the solution set, the variable x can be no bigger than 15.

In interval notation it would look something like this:

[15, ∞)

In set builder notation it would look something like this:

{x | x ∈ R, x ≤ 15}

It is read as "the set of all x, such that x is a member of the real numbers and x is less than or equal to 15".
7 0
3 years ago
Help help help help help help help help help help
Sergeu [11.5K]
Your answer should be 0.3000
5 0
3 years ago
Read 2 more answers
Cos(x+y)/cos(x)sin(y)=cot(y)-tan(x)
zhuklara [117]
So there is an identity we'll need to use to solve this:

cos(x+y) = cosxcosy - sinxsiny

replace the numerator with the right hand side of that identity and we get:

(cosxcosy - sinxsiny)/cosxsiny

Separate the numerator into 2 fractions and we get:

cosxcosycosxsiny- sinxsiny/cosxsiny

the cosx's cancel on the left fraction, the siny's cancel on the right fraction and we're left with:

cosy/siny - sinx/cosx

which simplifies to:

coty - tanx




7 0
3 years ago
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