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Marizza181 [45]

3 years ago

5

The average mark scored by 29 students in a science test was 56%. John was sick, so he sat the test late and scored 71%. Includi

ng John's score, what was the new mean mark?

1 answer:

Semenov [28]3 years ago

7 0

Answer:B

Step-by-step explanation:

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Find the value of x of this figure.

Bingel [31]

The sum of angles in a triangle is 180°
So:
(x+7) + (11x-9) +32 = 180
15x +30 = 180
15x = 180-30
15x = 150
x = 150/15
x = 10°

7 0

4 years ago

Please answer asap I need help

Andru [333]

you can right click inspect and see the correct answer

5 0

3 years ago

How many ml of a 20% acid mixture and a 80% acid mixture should be mixed to get 120ml of a 35% acid mixture?

shutvik [7]

Answer:

Volume of Mixture A =90 ml

Volume of Mixture B =30 ml

Step-by-step explanation:

Let say, Mixture A + Mixture B = Mixture C

Volume of Mixture A is x

Volume of Mixture B is y

So, Volume of Mixture C is x+y = 120 ml

Now, Acid contain in Mixture A is 20% =0.2x

Acid contain in Mixture B is 80% =0.8y

Also, Acid contain in Mixture C is 35% =(0.35)(x+y) = 0.35×120=42

Now, we know that,

Acid contain of Mixture A + Acid contain of Mixture B=Acid contain of Mixture C

∴ 0.2x+0.8y=42

∴ 2x+8y=420

We get two linear equations

2x+8y=420 and x+y = 120

Solving above equation...

∴ x=120-y

Replacing x value in 2x+8y=420

∴ 2(120-y)+8y=420

∴ 240-2y+8y=420

∴ 6y=180

∴ y=30

Replacing y value in any equation

∴ x=120-y=120-30=90

∴ x=90

Thus,

Volume of Mixture A is x=90 ml

Volume of Mixture B is y=30 ml

3 0

4 years ago

A circle has a radius of 9 inches. The Radius is multiplied by 2/3 to form a second circle. How is the ratio of the areas relate

liraira [26]

Answer:

$\frac {(Area\ of\ first\ circle) }{(Area\ of\ second\ circle)} = \frac{81}{36} = (\frac{r_{1} }{r_{2}}) ^{2}$

The above expression shows that ratios of the areas of the circles are equal to the square of the ratio of their radii.

Step-by-step explanation:

Radius of first circle $(r_{1})$ = 9 inches

Area of first circle = $\pi r_{1} ^{2}$

Area of first circle = 9 × 9 × π = 81 π

Now, since the radius is multiplied by 2/3 for from a new circle.

∴ Radius of the second circle = $9 \times \frac{2}{3} = 6\ inches$

Area of second circle = $\pi r_{2} ^{2}$

Area of second circle = 6 × 6 × π = 36 π

Now,

$\frac {(Area\ of\ first\ circle) }{(Area\ of\ second\ circle)} = \frac{81\pi }{36\pi }$

$\frac {(Area\ of\ first\ circle) }{(Area\ of\ second\ circle)} = \frac{81}{36} = (\frac{9}{6}) ^{2} = (\frac{r_{1} }{r_{2}}) ^{2}$

∵ $(r_{1})$ = 9 inches and $(r_{2})$ = 6 inches

The above expression shows that ratios of the areas of the circles are equal to the square of the ratio of their radii. i.e., $\frac {radius\ of\ first\ circle)^{2} }{(radius\ of\ second\ circle)^{2} } = \frac {(Area\ of\ first\ circle) }{(Area\ of\ second\ circle)}$

8 0

3 years ago

Which expression shows a way to find 50% of 632

Ilya [14]

Answer:

Well 50% of 632 is 316 but i need to see the expressions to be sure

Step-by-step explanation:

3 0

3 years ago