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sergejj [24]
3 years ago
13

SOMEONE ANSWER THIS QUICK!!

Mathematics
1 answer:
7nadin3 [17]3 years ago
5 0

Answer:

a= 9,15 b= 10,4

Step-by-step explanation:

You might be interested in
In a recent year, the ACT scores for the math portion of the test were normally distributed, with a mean of 21.1 and a standard
Natali5045456 [20]

Answer:

a) P(X

And we can find this probability using the normal standard table or excel:

P(z

b) P(19

And we can find this probability with this difference:

P(-0.396

And in order to find these probabilities we can use tables for the normal standard distribution, excel or a calculator.  

P(-0.396

c) P(X>26)=P(\frac{X-\mu}{\sigma}>\frac{26-\mu}{\sigma})=P(Z>\frac{26-21.1}{5.3})=P(z>0.925)

And we can find this probability using the complement rule and the normal standard table or excel:

P(z>0.925)=1- P(Z

d) We can consider unusual events values above or below 2 deviations from the mean

Lower = \mu -2*\sigma = 21.1 -2*5.3 =10.5

A value below 10.5 can be consider as unusual

Upper = \mu +2*\sigma = 21.1 +2*5.3 =31.7

A value abovr 31.7 can be consider as unusual

Step-by-step explanation:

Previous concepts

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 Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".  

Part a

Let X the random variable that represent the scores of a population, and for this case we know the distribution for X is given by:

X \sim N(21.1,5.3)  

Where \mu=21.1 and \sigma=5.3

We are interested on this probability

P(X

And the best way to solve this problem is using the normal standard distribution and the z score given by:

z=\frac{x-\mu}{\sigma}

If we apply this formula to our probability we got this:

P(X

And we can find this probability using the normal standard table or excel:

P(z

Part b

P(19

And we can find this probability with this difference:

P(-0.396

And in order to find these probabilities we can use tables for the normal standard distribution, excel or a calculator.  

P(-0.396

Part c

P(X>26)=P(\frac{X-\mu}{\sigma}>\frac{26-\mu}{\sigma})=P(Z>\frac{26-21.1}{5.3})=P(z>0.925)

And we can find this probability using the complement rule and the normal standard table or excel:

P(z>0.925)=1- P(Z

Part d

We can consider unusual events values above or below 2 deviations from the mean

Lower = \mu -2*\sigma = 21.1 -2*5.3 =10.5

A value below 10.5 can be consider as unusual

Upper = \mu +2*\sigma = 21.1 +2*5.3 =31.7

A value abovr 31.7 can be consider as unusual

6 0
3 years ago
C- 14b=<br><br> if c equals -7 and b equals 1/7
Andrew [12]
-7 -14(1/7)

remove parenthesis

14 * 1/7 = 2  (14/1 * 1/7 = 2/1 which we reduce to just 2)

-7 -2

-9
8 0
2 years ago
Find constants a and b such that the function y = a sin(x) + b cos(x) satisfies the differential equation y'' + y' − 7y = sin(x)
Elza [17]
The first thing we must do in this case is find the derivatives:
 y = a sin (x) + b cos (x)
 y '= a cos (x) - b sin (x)
 y '' = -a sin (x) - b cos (x)
 Substituting the values:
 (-a sin (x) - b cos (x)) + (a cos (x) - b sin (x)) - 7 (a sin (x) + b cos (x)) = sin (x)
 We rewrite:
 (-a sin (x) - b cos (x)) + (a cos (x) - b sin (x)) - 7 (a sin (x) + b cos (x)) = sin (x)
 sin (x) * (- a-b-7a) + cos (x) * (- b + a-7b) = sin (x)
 sin (x) * (- b-8a) + cos (x) * (a-8b) = sin (x)
 From here we get the system:
 -b-8a = 1
 a-8b = 0
 Whose solution is:
 a = -8 / 65
 b = -1 / 65
 Answer:
 
constants a and b are:
 
a = -8 / 65
 
b = -1 / 65
4 0
3 years ago
Identify the percent of change as an increase or a decrease.
vodomira [7]

Answer:

Increase

Step-by-step explanation:

The number gets larger. Increase means it gets larger, but decrease means it gets lower.

5 0
3 years ago
I dont need answers just an explaination how to solve these will give brailiest
ohaa [14]

Step-by-step explanation:

first you have to take all similar variable on the same side of the equation and the constants on the other side then solve the question .

example : -12x + 9 = -15x

-12x +15x = -9

3 x = -3

X = -3/3= -1

x = -1

like this you can solve all the other equation ..

<em>Hope </em><em>this </em><em>will </em><em>be</em><em> helpful</em><em> to</em><em> you</em><em> </em><em>.</em><em>.</em>

<em>plz </em><em>mark</em><em> my</em><em> answer</em><em> as</em><em> brainlist</em><em> </em><em>if </em><em>you</em><em> </em><em>find </em><em>it </em><em>useful</em><em>.</em><em>.</em>

5 0
3 years ago
Read 2 more answers
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