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4 years ago

Evaluate for a = 2 5a + 6 = _____

Mathematics

2 answers:

Aleksandr [31]4 years ago

7 0

5(2)+6

Pemdas

So 5(2)=10

Then add

10+6=16

aleksandrvk [35]4 years ago

5 0

Since a=2 it will be 5x2 which equal 10, plus 6

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Randomly selected students participated in an experiment to test their ability to determine when one minute (or sixty seconds)

zalisa [80]

Answer: $(57.41,\ 62.19)$

Step-by-step explanation:

Given : Sample size : $n=40$

Sample mean : $\overline{x}=59.8\text{ seconds}$

Standard deviation : $\sigma =9.2\text{ seconds}$

Significance level : $\alpha=1-0.9=0.1$

Critical value : $z_{\alpha/2}=1.645$

Formula to find the confidence interval for population mean :-

$\overline{x}\pm z_{\alpha/2}\dfrac{\sigma}{\sqrt{n}}\\\\=59.8\pm(1.645)\dfrac{9.2}{\sqrt{40}}\\\\\approx59.8\pm2.39\\\\=(59.8-2.39,\ 59.8+2.39)\\\\=(57.41,\ 62.19)$

Hence, a 90% confidence interval estimate of the population mean of all students = $(57.41,\ 62.19)$

6 0

3 years ago

In circle J with mZHLK = 18, find the mZHJK.

zysi [14]

Answer:

The measure of angle HJK is 36°

Step-by-step explanation:

In a circle, the measure of the inscribed angle equal half the measure of the central angle subtended by the same arc

In circle J

∵ J is the center of the circle

∵ H and K lie on the circle

∴ ∠HJK is a central angle subtended by arc HK

∵ L lies on the circle

∴ ∠HLK is an inscribed angle subtended by arc HK

→ By using the rule above

∵ ∠HJK and ∠HLK are the central angle and inscribed angle

subtended by the same arc HK

∴ m∠HLK = $\frac{1}{2}$ m∠HJK

∵ m∠HLK = 18°

∴ 18 = $\frac{1}{2}$ m∠HJK

→ Multiply both sides by 2

∴ 36 = m∠HJK

∴ The measure of angle HJK is 36°

3 0

3 years ago

1-(1.00375) exponent-12(30)

victus00 [196]

Answer:

360

Step-by-step explanation:

7 0

3 years ago

A doctor wants to estimate the mean HDL cholesterol of all 20- to 29-year-old females. The number of subjects needed to estima

Ludmilka [50]

Answer:

$n=(\frac{1.64(14.7)}{3})^2 =64.57 \approx 65$

So the answer for this case would be n=65 rounded up to the nearest integer

And the sample size would decrease by 160-65=95 subjects

Step-by-step explanation:

1) Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

$\bar X$ represent the sample mean for the sample

$\mu$ population mean (variable of interest)

s represent the sample standard deviation

n represent the sample size

ME represent the margin of error

The confidence interval for the mean is given by the following formula:

$\bar X \pm t_{\alpha/2}\frac{s}{\sqrt{n}}$ (1)

2) Solution to the problem

Since the new Confidence is 0.90 or 90%, the value of $\alpha=0.1$ and $\alpha/2 =0.05$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-NORM.INV(0.05,0,1)".And we see that $z_{\alpha/2}=1.64$