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3 years ago

30 points! please help!

Mathematics

2 answers:

Artemon [7]3 years ago

5 0

Answer:

Step-by-step explanation:

stiks02 [169]3 years ago

4 0

Answer:

Therefore

15.

$25c^{2}-9$

16.

$(y+8)(y+1)$

17.

$(x-3y)(x-7y)$

Step-by-step explanation:

15.

$(5c^{2} +3)(5c^{2}-3)$

Using the Identity (a + b)(a - b) = (a² - b²) we get

Consider here a = 5c and b = 3 then we will have

$((5c)^{2} -(3)^{2})=25c^{2}-9$ .....as required

16.

$y^{2}+9y+8$

Here Factorize 8 such that sum up to be 9

∴ 8 × 1 = 8 and 8 + 1 =9

$y^{2}+9y+8\\y^{2}+8y+y+8\\y(y+8)+1(y+8)\\(y+8)(y+1)$ ... as required

17.

$x^{2}-10xy+21y^{2}$

Here Factorize 21 such that sum up to be -10

∴ -3 × -7 = + 21 and -3 - 7 = - 10

$x^{2}-10xy+21y^{2}\\x^{2}-3xy-7xy+21y^{2}\\x(x-3y)-7y(x-3y)\\(x-3y)(x-7y)$ ........as required

Therefore

15.

$25c^{2}-9$

16.

$(y+8)(y+1)$

17.

$(x-3y)(x-7y)$

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Anita is years older than Basilio. Three times Anita's age added to six times Basilio's age is 36. 1. Define the variables 2. Cr

Scilla [17]

Answer :Anita's age = 7 years

Basilio's age = 2.5 years

Step 1. Assign variables to Anita's and Basilio's ages.

Anita's age = A

Basilio's age = B

Step 2. Use the information given to form two equations.

Anita is 4-1/2 years older than Basilio

A = 4.5 + B

Three times Anita's age added to six times Basilio's age is 36

3A + 6B = 36

Step 3. Substitute the value of A from first equation in to the second equation and solve for B

3(4.5 + B) + 6B = 36

13.5 + 3B + 6B = 36

13.5 + 9B = 36

9B = 36 - 13.5

9B = 22.5

B = 22.5/9 = 2.5

Step 4. Find the value of A

A = 4.5 + 2.5 = 7

Answer:

Anita's age = 7 years

Basilio's age = 2.5 years

6 0

3 years ago

The average THC content of marijuana sold on the street is 9.3%. Suppose the THC content is normally distributed with standard d

velikii [3]

Answer:

a) $X \sim N(9.3,1)$

b) $P(X>9.2)=P(\frac{X-\mu}{\sigma}>\frac{9.2-\mu}{\sigma})=P(Z>\frac{9.2-9.3}{1})=1-P(Z$

c) The value of height that separates the bottom 75% of data from the top 25% is 9.9745.

Step-by-step explanation:

1) 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".

2) Part a

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

$X \sim N(9.3,1)$

Where $\mu=9.3$ and $\sigma=1$

3) Part b

We are interested on this probability

$P(X>9.2)$

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:

$P(X>9.2)=P(\frac{X-\mu}{\sigma}>\frac{9.2-\mu}{\sigma})=P(Z>\frac{9.2-9.3}{1})=1-P(Z$

4) Part c

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

$P(X>a)=0.25$ (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 0.75 of the area on the left and 0.25 of the area on the right it's z=0.6745. On this case P(Z<0.6745)=0.75 and P(z>0.6745)=0.25

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

$P(X$