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2 years ago

A jug has 1 litre of 10% strength cordial. How much pure cordial needs to be added to make the strength 20%?

Mathematics

1 answer:

garik1379 [7]2 years ago

8 0

Answer:

The volume or amount of pure cordial to be added to the solution to make the strength 20% is 125 ml

Step-by-step explanation:

The given parameters, are;

The volume of cordial in the jug = 1 litre

The percentage strength of the cordial = 10%

The proportion of the cordial that contains pure cordial = 0.1

Therefore, the volume of pure cordial in the jug = 0.1 × 1 = 0.1 × 1000 ml = 100 ml

The volume of the solvent = The volume of the solution - The initial volume of pure cordial

∴ The volume of the solvent = 1000 ml - 100 ml = 900 ml

To increase the concentration of the cordial to 20% is given by the relation;

x/(x+900) = 0.2

Where;

x = The total volume of the pure cordial to be added to the pure solvent

Solving, gives;

x = 0.2×(x+900) = 0.2·x + 180

x -0.2·x = 180

0.8·x = 180

x = 180/0.8 = 225 ml

The total volume of the pure cordial to be added to the pure solvent = x = 225 ml

Therefore, the volume of pure cordial to be added to the initial volume of pure cordial in the solution, which is 100 ml, is therefore given as follows;

The volume or amount of pure cordial to be added = 225 ml - 100 ml = 125 ml.

The volume or amount of pure cordial to be added = 125 ml

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9/10 + 3/5

liubo4ka [24]

Answer:

15/10

Step-by-step explanation:

Since it is adding you need to get a common denominator(bottom number).

I know that 2 × 5 = 10 so now we multiply 3/5 × 2

we get 6/10

now the problem is 9/10 + 6/10

9 + 6 = 15 and the denominator is 10

15/10

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2 years ago

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5x +20 and 9x. Solve for X

Dennis_Churaev [7]

If u were to add 5x+20=9x you’d get x=5

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2 years ago

For the function defined by f(t)=2-t, 0≤t<1, sketch 3 periods and find:

Oksi-84 [34.3K]

The half-range sine series is the expansion for $f(t)$ with the assumption that $f(t)$ is considered to be an odd function over its full range, $-1$ . So for (a), you're essentially finding the full range expansion of the function

$f(t)=\begin{cases}2-t&\text{for }0\le t$

with period 2 so that $f(t)=f(t+2n)$ for $|t|$ and integers $n$ .

Now, since $f(t)$ is odd, there is no cosine series (you find the cosine series coefficients would vanish), leaving you with

$f(t)=\displaystyle\sum_{n\ge1}b_n\sin\frac{n\pi t}L$

where

$b_n=\displaystyle\frac2L\int_0^Lf(t)\sin\frac{n\pi t}L\,\mathrm dt$

In this case, $L=1$ , so

$b_n=\displaystyle2\int_0^1(2-t)\sin n\pi t\,\mathrm dt$
$b_n=\dfrac4{n\pi}-\dfrac{2\cos n\pi}{n\pi}-\dfrac{2\sin n\pi}{n^2\pi^2}$
$b_n=\dfrac{4-2(-1)^n}{n\pi}$

The half-range sine series expansion for $f(t)$ is then

$f(t)\sim\displaystyle\sum_{n\ge1}\frac{4-2(-1)^n}{n\pi}\sin n\pi t$

which can be further simplified by considering the even/odd cases of $n$ , but there's no need for that here.

The half-range cosine series is computed similarly, this time assuming $f(t)$ is even/symmetric across its full range. In other words, you are finding the full range series expansion for

$f(t)=\begin{cases}2-t&\text{for }0\le t$

Now the sine series expansion vanishes, leaving you with

$f(t)\sim\dfrac{a_0}2+\displaystyle\sum_{n\ge1}a_n\cos\frac{n\pi t}L$

where

$a_n=\displaystyle\frac2L\int_0^Lf(t)\cos\frac{n\pi t}L\,\mathrm dt$

for $n\ge0$ . Again, $L=1$ . You should find that

$a_0=\displaystyle2\int_0^1(2-t)\,\mathrm dt=3$

$a_n=\displaystyle2\int_0^1(2-t)\cos n\pi t\,\mathrm dt$
$a_n=\dfrac2{n^2\pi^2}-\dfrac{2\cos n\pi}{n^2\pi^2}+\dfrac{2\sin n\pi}{n\pi}$
$a_n=\dfrac{2-2(-1)^n}{n^2\pi^2}$

Here, splitting into even/odd cases actually reduces this further. Notice that when $n$ is even, the expression above simplifies to

$a_{n=2k}=\dfrac{2-2(-1)^{2k}}{(2k)^2\pi^2}=0$

while for odd $n$ , you have

$a_{n=2k-1}=\dfrac{2-2(-1)^{2k-1}}{(2k-1)^2\pi^2}=\dfrac4{(2k-1)^2\pi^2}$

So the half-range cosine series expansion would be

$f(t)\sim\dfrac32+\displaystyle\sum_{n\ge1}a_n\cos n\pi t$
$f(t)\sim\dfrac32+\displaystyle\sum_{k\ge1}a_{2k-1}\cos(2k-1)\pi t$
$f(t)\sim\dfrac32+\displaystyle\sum_{k\ge1}\frac4{(2k-1)^2\pi^2}\cos(2k-1)\pi t$

Attached are plots of the first few terms of each series overlaid onto plots of $f(t)$ . In the half-range sine series (right), I use $n=10$ terms, and in the half-range cosine series (left), I use $k=2$ or $n=2(2)-1=3$ terms. (It's a bit more difficult to distinguish $f(t)$ from the latter because the cosine series converges so much faster.)