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Aleksandr [31]
3 years ago
13

When an opinion poll selects cell phone numbers at random to dial, the cell phone exchange is first selected and then random dig

its are added to form a complete telephone number. When using this procedure to generate random cell phone numbers, approximately 55%55% of the cell numbers generated correspond to working numbers. You watch a pollster dial 1515cell numbers that have been selected in this manner.What is the mean number of calls that reach a working cell number?A. 0.550.55B. 1515C. 8.258.25D. 3030
Mathematics
1 answer:
Sav [38]3 years ago
6 0

Answer:

A

Step-by-step explanation:

When an opinion poll selects cell phone numbers at random to dial, the cell phone exchange is first selected and then random digits are added to form a complete telephone number. When using this procedure to generate random cell phone numbers, approximately 55%55% of the cell numbers generated correspond to working numbers. You watch a pollster dial 1515cell numbers that have been selected in this manner.What is the mean number of calls that reach a working cell number?A. 0.550.55B. 1515C. 8.258.25D. 3030

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If Ben invests $4500 at 4% interest per year, how much additional money must he invest at 5 1/2% annual interest to ensure that
pogonyaev

Step \; 1: \; Assing \; variable \; for \; the \; unknown \; that \; we \; need \; to \; find.\\Let \; x \; be \; additional \; money \; invested

Step \; 2: \; Use \; the \; appropriate \; formula \; of \; simple \; interest \; set \; up \; an \; equation\\Interest \; earned \; each \; year = \; Amount \; invested \times annual \; rate \; of \; interest\\\\Amount \; invested \; in \; 4 \% \; rate \; of \; interest=\$4500\\Amount \; invested \; in \; 5\frac{1}{2}\% \; rate \; of \; interest= \$x\\Amount \; invested \; totally \; in \; 4\frac{1}{2}\% \; rate \; of \; interest = \$(4500+x)

Interest \; earned \; in \; 4\% \; interest \; rate\\ = \; 4500(4\%)=180\\Interest \; earned \; in \; 5\frac{1}{2}\% \; interest \; rate\\ = x(5\frac{1}{2}\%)=0.055x\\Interest \; earned \; totally \; in \; 4\frac{1}{2}\% \; interest \; rate = (4500+x)(4\frac{1}{2}\%)\\=0.045(4500+x)

\\\\So, \; the \; equation \; would \; be:\\180+0.055x=0.045(4500+x)

Step \; 1: \; Distribute \; 0.045 \; in \; the \; right \; side\\180+0.055x=202.5+0.045x\\\\Step \; 2: \; Subtract \; 0.045x \; and \; 180 \; on \; both \; sides \; to \; get \; x \; alone\\0.055x-0.045x=202.5-180\\\\Step \; 3: \; Combine \; Like \; Terms\\0.01x=22.5\\\\Step \; 4: Divide \; 0.01 \; on \; both \; sides\\\frac{0.01x}{0.01}=\frac{22.5}{0.01}\\\\Step \; 5: \; Simplifying \; fraction \; on \; both \; sides\\x=2250

\underline{Conclusion:}\\Ben \; should \; invest \; additional \; money \; of \; \$2250

5 0
4 years ago
Athena bought x boxes of cookies to bring to a party. Each box contains 10 cookies. She decides to keep two boxes for herself. S
mash [69]

Given parameters:

Number of boxes Athena bought for the party  = x

Number of cookies per box = 10

Number of cookies she brought to the party = 70

Number removed  = 2 boxes

Unknown:

Equation of the number of boxes = ?

Solution:

    1 box of cookies contains 10 cookies

If Athena, removed 2 boxes, in those two boxes, we have 20 cookies

 Total number of cookies  = 70 + 20 = 90 cookies;

So;

    x  = \frac{total number of cookies}{number of cookies per box}

   Therefore;

                    x  = \frac{90}{10}boxes

7 0
3 years ago
What is the solution for the following equation?<br> x^2-6x+9=11
tankabanditka [31]
Make one side equal zero
minus 11 to both sides
x^2-6x-2=0
another quadratic equation

if you hahve
ax^2+bx+c=0
x=\frac{-b+/- \sqrt{b^{2}-4ac} }{2a}

1x^2-6x-2=0
a=1
b=-6
c=-2

x=\frac{-(-6)+/- \sqrt{(-6)^{2}-4(1)(-2)} }{2(1)}
x=\frac{6+/- \sqrt{36+8} }{2}
x=\frac{6+/- \sqrt{44} }{2}
x=\frac{6+/- 2\sqrt{11} }{2}
x=3+/- \sqrt{11}
x=3+ \sqrt{11} or 3- \sqrt{11}

aprox
x=6.31662 or -0.316625
4 0
3 years ago
Rebecca had these results when she drew 10 tiles from the bag. The bag has a total of 20 tiles. Her classmates got similar resul
7nadin3 [17]

Answer: 15 green 5 red

Step-by-step explanation:

if its less likely to pull red than green you would to chose the lowest amount

8 0
3 years ago
Read 2 more answers
Please help solve this, I’ve tried my best. My answers are a height of 6.7 using 30-60-90 as a last resort, and the glass volume
Neko [114]

Answer:

A) To ensure the correct and exact straight height

B) 15 inches

C) 24.87 in^{3}

Step-by-step explanation:

Hello! Lets start!

First, it asks us to explain why the two bases must be parallel. In order to measure the correct and exact height, we must be sure that the bases are parallel, or else there would be a range of heights; in order to ensure that you are measuring a straight distance, they must be parallel!

Second, it asks us to identify the height of cone. To do this, we must make a slope! We can see that, for every time we go down 5 inches, we lose 1 inch of our base! Our slope in this situation would be -5. So, lets continue to see how long before the cone reaches its tip, in which the base would be equal to 0. At 5 inches, our base is 2 inches. At 10 inches, our base is 1 inch. At 15 inches, we do not have a base, as it equals 0! So therefore, our cone height is 15 inches.

Third, it asks us to identify the volume of the cup, which is also called a <em>circular truncated cone. </em>To do so, we can use the formula:

₁V = \frac{1}{3} \pi (r_{1}^2 + r_{1}r_{2} + r_2^2)h

Lets plug in our information!

V = \frac{1}{3} \pi (1.5^{2} + (1.5)(1) + 1^{2}) (5)\\V = 24.87

Hope this helps! Remember, math is fun!

3 0
3 years ago
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