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3 years ago

How old was Sarah x years ago if she is now 23?

Mathematics

2 answers:

kobusy [5.1K]3 years ago

8 0

Answer:

23-x

Step-by-step explanation:

vovikov84 [41]3 years ago

7 0

Answer:

23 - x

Is that all there is to the problem?

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A rubber belt connects the two flywheels shown. Find the total

elena-s [515]

Answer:

$L\approx 29.43\,in$

Step-by-step explanation:

The total length of the belt is:

$L = 2\pi\cdot (1.5\,in) + 20\,in$

$L\approx 29.43\,in$

4 0

3 years ago

Read 2 more answers

Pure copper was mixed with a 10% copper alloy to produce an alloy thát was 25% copper. How much of the pure copper and how much

lora16 [44]

Answer:

6kg pure copper and 30 kg 10% copper was mixed to give 36kg of 25% alloy

Step-by-step explanation:

Here, we want to produce 36 kg of 25% alloy

Let the Pure copper be x kg while 10% alloy be y kg

Pure copper is simply 100% copper

Thus;

x + y = 36 •••••(i)

Then;

100% of x + 10% of y = 25% of 36

= x + 0.1y = 9 •••••• ii)

From i x = 36-y

from ii, x = 9-0.1y

Equate both x

36-y = 9-0.1y

36-9 = 0.1y + y

0.9y = 27

y = 27/0.9

y = 30

x = 36-y

x = 36-30

x = 6 kg

8 0

3 years ago

Find the sum of a finite geometric sequence from n=1 to n=8, using the expression -2(3)^n-1

MissTica

$\bf \qquad \qquad \textit{sum of a finite geometric sequence}
\\\\
S_n=\sum\limits_{i=1}^{n}\ a_1\cdot r^{i-1}\implies S_n=a_1\left( \cfrac{1-r^n}{1-r} \right)\quad 
\begin{cases}
n=n^{th}\ term\\
a_1=\textit{first term's value}\\
r=\textit{common ratio}
\end{cases}
\\\\\\
\sum\limits_{n=1}^{8}~-2(3)^{n-1}~~
\begin{cases}
n=8\\
a_1=-2\\
r=3
\end{cases}\implies S_8=-2\left( \cfrac{1-3^8}{1-3} \right)
\\\\\\
S_8=\underline{-2}\left( \cfrac{1-6561}{\underline{-2}} \right)\implies s_8=1-6561\implies S_8=-6560$