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3 years ago

Figure the standard deviation of the distribution of means for a population with a standard deviation of 20 and sample size of 1

Mathematics

1 answer:

mart [117]3 years ago

6 0

Answer:

standard deviation of the distribution = 6.325.

Step-by-step explanation:

i) standard deviation of the population σ = 20

ii) size of sample n = 10.

iii) standard deviation of the distribution = $\frac{\sigma}{\sqrt{n}} = \frac{20}{\sqrt{10}} = \frac{20}{3.162} = 6.325$

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Sandra throws an object straight up into the air with initial velocity of 38 ft per square from platform that is 30 ft above the

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Answer:

3 seconds.

Step-by-step explanation:

We have been given that Sandra throws an object straight up into the air with initial velocity of 38 ft per second from platform that is 30 ft above the ground.

To find the time it will take for object to hit the ground, we will use formula:

$h(t)=-16t^2+v_0t+h_0$ , where, $v_0$ represents initial velocity and $h_0$ represents initial height.

Upon substituting our given initial velocity and initial height, we will get:

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We know that object will hit the ground, when height will be 0, so we will equate object's height equal to 0 and solve for t as:

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Divide by 2:

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Upon using quadratic formula, we will get:

$t=\frac{-b\pm\sqrt{b^2-4ac}}{2a}=\frac{-19\pm\sqrt{19^2-4(-8)(15)}}{2(-8)}$

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2 years ago

In a random sample of 400 residents of Boston, 320 residents indicated that they voted for Obama in the last presidential electi

coldgirl [10]

Answer:

C.I = 0.7608 ≤ p ≤ 0.8392

Step-by-step explanation:

Given that:

Let consider a random sample n = 400 candidates where 320 residents indicated that they voted for Obama

probability $\hat p = \dfrac{320}{400}$

= 0.8

Level of significance ∝ = 100 -95%

= 5%

= 0.05

The objective is to develop a 95% confidence interval estimate for the proportion of all Boston residents who voted for Obama.

The confidence internal can be computed as:

$=\hat p \pm Z_{\alpha/2} \sqrt{\dfrac{ p(1-p)}{n } }$

where;

$Z_{0.05/2}$ = $Z_{0.025}$ = 1.960

SO;

$=0.8 \pm 1.960 \sqrt{\dfrac{ 0.8(1-0.8)}{400 } }$

$=0.8 \pm 1.960 \sqrt{\dfrac{ 0.8(0.2)}{400 } }$

$=0.8 \pm 1.960 \sqrt{\dfrac{ 0.16}{400 } }$

$=0.8 \pm 1.960 \sqrt{4 \times 10^{-4}}$

$=0.8 \pm 1.960 \times 0.02}$

$=0.8 \pm 0.0392$

= 0.8 - 0.0392 OR 0.8 + 0.0392

= 0.7608 OR 0.8392

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2 years ago

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