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3 years ago

Write some thing good in answer.

Mathematics

2 answers:

denis23 [38]3 years ago

5 0

Answer:

You’re awesome.

ki77a [65]3 years ago

4 0

Answer:

some thing good in answer.

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In a fifth grade class 4/5 of the girls have brown hair. Of the brown-haired girls, 3/4 of them have long hair. Of the girl with

Aleks [24]

lets say there are 100 girls.
4/5 of 100 is 80, so 80 girls have brown hair.
3/4 of the 80 who have brown hair have long hair.
3/4 of 80 is 60.
so we know that out of 100, 60 have long brown hair.
in simplest fraction form, 60/100= 3/5

8 0

3 years ago

It is known that the population variance equals 484. With a .95 probability, the sample size that needs to be taken to estimate

Hitman42 [59]

Answer:

The minimum sample size is n = 75 so that the desired margin of error is 5 or less.

Step-by-step explanation:

We are given the following in the question:

Population variance = 484

Standard deviation =

$\sigma^2 = 484\\\sigma =\sqrt{484} = 22$

Confidence level = 0.95

Significance level = 0.05

Margin of error = 5

Formula:

Margin of error =

$E = z\times \dfrac{\sigma}{\sqrt{n}}\\\\n = (\dfrac{z\times \sigma}{E})^2$

$z_{critical}\text{ at}~\alpha_{0.05} = 1.96$

Putting values, we get

$E\leq 5\\\\1.96\times \dfrac{22}{\sqrt{n}} \leq 5\\\\\sqrt{n} \geq 1.96\times \dfrac{22}{5}\\\\n \geq (1.96\times \dfrac{22}{5})^2\\\\n \geq 74.373$

Thus, the minimum sample size is n = 75 so that the desired margin of error is 5 or less.

3 0

3 years ago

Find the common ratio of the geometric sequence 11, -55, 275,...11,−55,275,...

Kaylis [27]

Answer:

r = -5

Step-by-step explanation:

common ratio (r) is found be dividing one term by its preceding term:

r = 275 ÷ -55 = -5

or, r = -55 ÷ 11 = -5

Therefore, r = -5

3 0

2 years ago

The area of a rectangle is 38.25 square yards and its base is 9 yards. What is the height? Do not round your answer.

devlian [24]

Answer:

4.25 yards

Step-by-step explanation:

38.25/9=4.25

7 0

3 years ago

Read 2 more answers

A scientist needs to make 2 liters of saline solution (salt water), in which the salt level must be at 15% concentration (meanin

slamgirl [31]

Answer:

We need 1.6 liters of the 10 % concentration level and saline solution and 0.4 liters of the 35 % concentration level and saline solution.

Step-by-step explanation:

Let V₁ be the volume of the 10% concentration saline solution required and V₂ be the volume of 35% concentration saline solution required.

Since mass = concentration × volume, the total mass of the 10% and 35% volume saline solution equal the mass of the 2 liter 15% volume solution.

So, 0.1V₁ + 0.35V₂ = 2 × 0.15

0.1V₁ + 0.35V₂ = 0.3 (1)

Also, the total volume of the 15 % solution must equal 2 liters. So,

V₁ + V₂ = 2 (2)

V₁ = 2 - V₂ (3)

putting equation (3) into equation (1), we have

0.1(2 - V₂) + 0.35V₂ = 0.3

0.2 - 0.1V₂ + 0.35V₂ = 0.3

we now collect terms, so

- 0.1V₂ + 0.35V₂ = 0.3 - 0.2

0.25V₂ = 0.1

we now divide through by 0.25, so

V₂ = 0.1/0.25

V₂ = 0.4 liters

we now put V₂ into (3), we have,

V₁ = 2 - 0.4

V₁ = 1.6 liters

So, we need 1.6 liters of the 10 % concentration level and saline solution and 0.4 liters of the 35 % concentration level and saline solution.

3 0

3 years ago