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Semenov [28]
3 years ago
12

Expand the expression -7k (k - 3)

Mathematics
1 answer:
nataly862011 [7]3 years ago
3 0
Your answer will be b
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normally distributed with mean 24.6 seconds and standard deviation 0.64 seconds;the lower finishing time, the better. If the qua
marshall27 [118]

Answer:

z=1.04

And if we solve for a we got

a=24.6 +1.04*0.64=25.27

So the value of height that separates the bottom 85% of data from the top 15% is 25.27.  

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".  

Solution to the problem

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

X \sim N(24.6,0.64)  

Where \mu=24.6 and \sigma=0.64

Solution to the problem

For this part we want to find a value a, such that we satisfy this condition:

P(X>a)=0.15   (a)

P(X   (b)

Both conditions are equivalent on this case. We can use the z score again in order to find the value a.  

As we can see on the figure attached the z value that satisfy the condition with 0.85 of the area on the left and 0.15 of the area on the right it's z=1.04. On this case P(Z<1.04)=0.85 and P(z>1.04)=0.15

If we use condition (b) from previous we have this:

P(X  

P(z

But we know which value of z satisfy the previous equation so then we can do this:

z=1.04

And if we solve for a we got

a=24.6 +1.04*0.64=25.27

So the value of height that separates the bottom 85% of data from the top 15% is 25.27.  

3 0
3 years ago
What is the inverse of Y=-5x-7
Pepsi [2]

Answer:y = - 5x - 7

Step-by-step explanation:The equation of a line in slope- intercept form is

y = mx + b ( m is the slope and b the y- intercept )

here m = - 5 and b = - 7, hence

y = - 5x - 7 ← equation of line

7 0
3 years ago
Please help i don’t understand this
avanturin [10]

Answer:

Step-by-step explanation:

The solution is in the attached file

3 0
2 years ago
£70 is divided between Natasha, Richard &amp; Stephen so that Natasha gets twice as much as Richard, and Richard gets three time
Mekhanik [1.2K]

Answer:

  £42

Step-by-step explanation:

The ratio of Richard's amount to Stephen's amount is ...

  R : S = 3 : 1

The ratio of Natasha's amount to Richard's amount is ...

  N : R = 2 : 1 = 6 : 3

Then the ratio of all three amounts is ...

  N : R : S = 6 : 3 : 1

The proportion of the total that Natasha gets is ...

  6/(6+3+1) = 6/10

so she gets ...

  (6/10)×£70 = £42

Natasha gets £42.

5 0
3 years ago
Multiply and simplify. 2x^4yx⋅6xy^2z^3
Mrac [35]
The answer is letter a
4 0
3 years ago
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