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Anarel [89]
3 years ago
8

(a) if each of them tells 1 person, and then everybody tells exactly 1 other person, and so on, how long will it take until all

450 students in the school hear the rumor? assume that the rate for telling the next person is 1 hour. that is, initially jack and jill know; after 1 hour, 2 more people know; after 2 hours, 2 more people know, . . . .
Mathematics
1 answer:
luda_lava [24]3 years ago
8 0
For this problem I recommend using the explicit version of the arithmetic sequence formula
an = a1 + (n – 1)d.

The first term is a1, the common difference is d, and the number of terms is n. an is the final number we are looking for.


We shall substitute in the common difference and 2 since every hour 2 more people will know. Also the first term is equal to 2. an is 450 because that's what we are looking for.


the equation looks like 450= 2 + (n – 1)2. Now we evaluate. n = 225. 225 terms will pass, then all 450 students will know the rumor. Each term will equal 1 hour . 225 hours converts to 9 full days and 9 hours. So it will take 9 days and 9 hours for every student to know the rumor at that rate.
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Bus stop Restaurant sell 3/4 as many cheeseburgers as they do with hamburgers on any given day. If there are a total of 42 burge
schepotkina [342]

Answer:

24cb 18 hb

Step-by-step explanation:

Let's call C the number of cheese burger sold and H the number of hamburgers.

As the cheeseburger sold are 3/4 of hamburgers, we can represent with the following equation:

C= (3/4)H (equation 1)

The total of burgers sold are the total of cheeseburger plus the total of hamburgers, and the sum 42. The equation representing it is:

C + H = 42

Replacing C by its value of eq. 1:

(3/4)H + H = 42

(3/4)H + (4/4)H = 42

(7/4) H = 42

Dividing both sides by (7/4)

H = 42/(7/4)

H= 42*(4/7)

H= (42/7)*4

H= 6*4

H=24

Then, C is:

C=(3/4)H

C=(3/4)*24

C= 3*24/4

C=72/4

C=18

We can verify it summing C+H

C+H=24+18=42 verified!

6 0
3 years ago
Find the area of the following parallelogram:​
nalin [4]

Answer:

216

Step-by-step explanation:

18 which is the base will be multiplied by the height which is 12 giving you

18 x 12 = 216

6 0
3 years ago
Please help!!<br> Write a matrix representing the system of equations
frozen [14]

Answer:

(4, -1, 3)

Step-by-step explanation:

We have the system of equations:

\left\{        \begin{array}{ll}            x+2y+z =5 \\    2x-y+2z=15\\3x+y-z=8        \end{array}    \right.

We can convert this to a matrix. In order to convert a triple system of equations to matrix, we can use the following format:

\begin{bmatrix}x_1& y_1& z_1&c_1\\x_2 & y_2 & z_2&c_2\\x_3&y_2&z_3&c_3 \end{bmatrix}

Importantly, make sure the coefficients of each variable align vertically, and that each equation aligns horizontally.

In order to solve this matrix and the system, we will have to convert this to the reduced row-echelon form, namely:

\begin{bmatrix}1 & 0& 0&x\\0 & 1 & 0&y\\0&0&1&z \end{bmatrix}

Where the (x, y, z) is our solution set.

Reducing:

With our system, we will have the following matrix:

\begin{bmatrix}1 & 2& 1&5\\2 & -1 & 2&15\\3&1&-1&8 \end{bmatrix}

What we should begin by doing is too see how we can change each row to the reduced-form.

Notice that R₁ and R₂ are rather similar. In fact, we can cancel out the 1s in R₂. To do so, we can add R₂ to -2(R₁). This gives us:

\begin{bmatrix}1 & 2& 1&5\\2+(-2) & -1+(-4) & 2+(-2)&15+(-10) \\3&1&-1&8 \end{bmatrix}\\\Rightarrow\begin{bmatrix}1 & 2& 1&5\\0 & -5 & 0&5 \\3&1&-1&8 \end{bmatrix}

Now, we can multiply R₂ by -1/5. This yields:

\begin{bmatrix}1 & 2& 1&5\\ -\frac{1}{5}(0) & -\frac{1}{5}(-5) & -\frac{1}{5}(0)& -\frac{1}{5}(5) \\3&1&-1&8 \end{bmatrix}\\\Rightarrow\begin{bmatrix}1 & 2& 1&5\\ 0 & 1 & 0& -1 \\3&1&-1&8 \end{bmatrix}

From here, we can eliminate the 3 in R₃ by adding it to -3(R₁). This yields:

\begin{bmatrix}1 & 2& 1&5\\ 0 & 1 & 0& -1 \\3+(-3)&1+(-6)&-1+(-3)&8+(-15) \end{bmatrix}\\\Rightarrow\begin{bmatrix}1 & 2& 1&5\\ 0 & 1 & 0& -1 \\0&-5&-4&-7 \end{bmatrix}

We can eliminate the -5 in R₃ by adding 5(R₂). This yields:

\begin{bmatrix}1 & 2& 1&5\\ 0 & 1 & 0& -1 \\0+(0)&-5+(5)&-4+(0)&-7+(-5) \end{bmatrix}\\\Rightarrow\begin{bmatrix}1 & 2& 1&5\\ 0 & 1 & 0& -1 \\0&0&-4&-12 \end{bmatrix}

We can now reduce R₃ by multiply it by -1/4:

\begin{bmatrix}1 & 2& 1&5\\ 0 & 1 & 0& -1 \\ -\frac{1}{4}(0)&-\frac{1}{4}(0)&-\frac{1}{4}(-4)&-\frac{1}{4}(-12) \end{bmatrix}\\\Rightarrow\begin{bmatrix}1 & 2& 1&5\\ 0 & 1 & 0& -1 \\0&0&1&3 \end{bmatrix}

Finally, we just have to reduce R₁. Let's eliminate the 2 first. We can do that by adding -2(R₂). So:

\begin{bmatrix}1+(0) & 2+(-2)& 1+(0)&5+(-(-2))\\ 0 & 1 & 0& -1 \\0&0&1&3 \end{bmatrix}\\\Rightarrow\begin{bmatrix}1 & 0& 1&7\\ 0 & 1 & 0& -1 \\0&0&1&3 \end{bmatrix}

And finally, we can eliminate the second 1 by adding -(R₃):

\begin{bmatrix}1 +(0)& 0+(0)& 1+(-1)&7+(-3)\\ 0 & 1 & 0& -1 \\0&0&1&3 \end{bmatrix}\\\Rightarrow\begin{bmatrix}1 & 0& 0&4\\ 0 & 1 & 0& -1 \\0&0&1&3 \end{bmatrix}

Therefore, our solution set is (4, -1, 3)

And we're done!

3 0
3 years ago
A student who correctly answered 60 questions a test received a score of 75%. How many questions were on the test
Iteru [2.4K]
It would be 45 you take 60 x 75%


7 0
3 years ago
Merideth measured 3.25 cups of flour and 1.625 cups of brown sugar into
Fiesta28 [93]

Answer:

Step-by-step explanation:

This is just an addition question. If you have a calculator just add the numbers.

3.25 + 1.625 = 4.875 cups in the bowl.

Sometimes you can use another method. Sometimes it is shorter.

3 1/4 + 1 5/8 = 3 2/8 + 1 5/8 = 4 7/8.

7/8 = 0.875

3 0
4 years ago
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