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horrorfan [7]
3 years ago
7

21-m=9 anyone know this ?

Mathematics
2 answers:
prisoha [69]3 years ago
6 0

Answer:

m=12

Step-by-step explanation:

21-m=9

-m=9-21

-m=-12

m=12

lord [1]3 years ago
4 0

Answer:

12

Step-by-step explanation:

21-m=9

21-9=12

m=12

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A lock has four dials. On each dial are the digits 0 to 9 how many possible combinations are there
madam [21]

Answer:

10,000

Step-by-step explanation:

The combination consists of four digits, hence 0000 to 9999. There at 10^4 or 10,000 possible combinations (but only one that works).

7 0
3 years ago
19. A cross section of a water trough is in the shape of trapezoid with bases measuring 4 m and 12 m. what is the length of the
ludmilkaskok [199]

Given:

The bases of trapezoid measuring 4 m and 12 m.

To find:

The median of the trapezoid.

Solution:

The median of the trapezoid is the average of its bases.

\text{Median}=\dfrac{\text{Upper base + Lower base}}{2}

The bases of trapezoid measuring 4 m and 12 m. So, the median of the trapezoid is:

\text{Median}=\dfrac{4+12}{2}

\text{Median}=\dfrac{16}{2}

\text{Median}=8

Therefore, the correct option is C.

5 0
3 years ago
A physical fitness association is including the mile run in its secondary-school fitness test. The time for this event for boys
Luba_88 [7]

Answer:

z=-1.28

And if we solve for a we got

a=470 -1.28*60=393.2

So the value of height that separates the bottom 10% (Fastest 10%) of data from the top 90% is 393.2.

so if the time is 393.2 or lower a boy would earn a certificate of recognition from the fitness association

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 time for this event of a population, and for this case we know the distribution for X is given by:

X \sim N(470,60)  

Where \mu=470 and \sigma=60

NOTE: For this case the fastest 10% is on the lower tail of the distribution

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

P(X>a)=0.9   (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 0.1 of the area on the left and 0.9 of the area on the right it's z=-1.28. On this case P(Z<-1.28)=0.1 and P(z>-1.28)=0.9

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=-1.28

And if we solve for a we got

a=470 -1.28*60=393.2

So the value of height that separates the bottom 10% (Fastest 10%) of data from the top 90% is 393.2.

so if the time is 393.2 or lower a boy would  earn a certificate of recognition from the fitness association

4 0
3 years ago
Why is it unimportant to have the same powers of 10 we multiplying and dividing in Scientific Notation
nikdorinn [45]
We only need to worry about the exponents
6 0
3 years ago
Read 2 more answers
Pls help 30 points 7th grade math
Vlada [557]
Z>7 I think that’s the answer let me know if it’s right or not
5 0
3 years ago
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