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3 years ago

280 is what percent of 400?

Mathematics

2 answers:

skad [1K]3 years ago

4 0

It would be 70% of 400

490(.7) = 280

bazaltina [42]3 years ago

4 0

It would be 7% because .7 is a decimal so if you convert it into a percent it will be 7%

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A certain pipe can be used to fill a pool with water in 2 hours. A second pipe can be used to fill the pool in 4 hours. How long

Kryger [21]

Answer:

1 1/3 hours

Step-by-step explanation:

Pipe 1 alone:

fills the pool in 2 hours

in 1 hour, it fills 1/2 of the pool

Pipe 2 alone:

fills the pool in 4 hours

in 1 hour, it fills 1/4 of the pool

Pipe 1 and Pipe 2 working together:

fill the pool in x hours

in 1 hour, they fill 1/x of the pool

Working together, in 1 hour the two pipes fill 1/2 + 1/4 of the pool.

Working together, in 1 hour the two pipes fill 1/x of the pool.

Therefore,

1/2 + 1/4 = 1/x

2/4 + 1/4 = 1/x

3/4 = 1/x

x = 4/3

x = 1 1/3

Answer: 1 1/3 hours

6 0

3 years ago

the figure below shows a circle centre of radius 10 cm the chord PQ=16cm calculate the area of the shaded region

m_a_m_a [10]

Step-by-step explanation:

OPQ originally forms a sector, the formula for sector is

$\frac{x}{360} \pi {r}^{2}$

where x is the degrees of rotation between the two radii.

We know three sides length and is trying to find an angle between the radii so we can use law of cosines which states that

$16 = \sqrt{10 {}^{2} + 10 {}^{2} - 2(100) \times \cos(o) }$

This isn't the standard formula, it's for this problem

$16 = \sqrt{200 - 200 \times \cos(o) }$

$16 = \sqrt{200 - 200 \cos(o) }$

$256 = 200 - 200 \cos(o)$

$56 = - 200 \cos(o)$

$- \frac{7}{25} = \cos(o)$

$\cos {}^{ - 1} ( - \frac{7}{25} ) = \cos {}^{ - 1} ( \cos(o) )$

$106.26 = o$

So we found our angle of rotation, which is 106.26

Now, we do the sector formula.

$\frac{106.26}{360} (100)\pi$

$\frac{10626}{360} \pi$

is the area of sector.

Now let find the area of triangle, we can use Heron formula,

The area of a triangle is

$\sqrt{s(s - a)(s - b)(s - c)}$

where s is the semi-perimeter.

To find s, add all the side lengths up, 10,10,16 and divide it by 2.

Which is

$\frac{36}{2} = 18$

$\sqrt{18(18 - 10)(18 - 10)(18 - 16)}$

$\sqrt{18(8)(8)(2)}$

$\sqrt{(36)(64)}$

$6 \times 8 = 48$

So our area of the triangle is 48. Now, to find the shaded area subtract the main area,( the sector of the circle) by the area of the triangle so we get

$\frac{10626}{360} - 48$

Which is an approximate or

44.73

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2 years ago

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vlabodo [156]

Answer:

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Step-by-step explanation:

4 0

2 years ago

What is the solution to the linear system of equations?

notsponge [240]

The answer is C

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3 0

3 years ago

25x89 divided by 1/4

jeka94

Answer:

8900

Step-by-step explanation:

25x89=2225

2225/(1/4)= 8900

6 0

3 years ago