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3 years ago

How do you find percent of a number mentally

2 answers:

6 0

Percentage of a number using mental math. Learn how to solve percent problems in your head! Since 10% is 1/10, and it's so easy to find 1/10 of any number, we can use that to quickly calculate certain percentages of quantities in our heads. to find 20% of a number, first find 10% of it, and double that.

olga55 [171]3 years ago

5 0

It isn't easy really but you can always divide the number out. For example 50% of 200 is 100 by dividing 200 by 2 or 25% of 100 is 25 by dividing 100 by 4 since 25% is equivalent to 1/4

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A hypothesis test is to be performed for a population proportion. For the given sample data and null hypothesis, compute the val

liberstina [14]

Answer:

The correct option is a

Step-by-step explanation:

From the question we are told that

The sample size is n = 415

The sample proportion is $\r p = 0.49$

Now

The null hypothesis is $H_o : p = 0.3$

The alternative hypothesis is $H_a : p \ne 0.3$

The test statistics is mathematically evaluated as

$t = \frac{\r p - p }{ \frac{\sqrt{ p (1- p )} }{n} }$

substituting values

$t = \frac{0.49 - 0.3 }{ \sqrt{ \frac{0.3 (1- 0.3 ) }{415} }}$

$t = 8.446$

8 0

4 years ago

Is -3 an expression

Natalija [7]

Answer:

yeah it is an expression

Explanation:

An expression may refer to any of the following:

A combination of letters, numbers, or symbols used to represent a value of a variable. ..

4 0

3 years ago

A researcher compares two compounds (1 and 2) used in the manufacture of car tires that are designed to reduce braking distances

wariber [46]

Answer:

Step-by-step explanation:

Hello!

The objective of this experiment is to compare two compounds, designed to reduce braking distance, used in tire manufacturing to prove if the braking distance of SUV's equipped with tires made with compound 1 is shorter than the braking distance of SUV's equipped with tires made with compound 2.

So you have 2 independent populations, SUV's equipped with tires made using compound 1 and SUV's equipped with tires made using compound 2.

Two samples of 81 braking tests are made and the braking distance was measured each time, the study variables are determined as:

X₁: Braking distance of an SUV equipped with tires made with compound one.

Its sample mean is X[bar]₁= 69 feet

And the Standard deviation S₁= 10.4 feet

X₂: Braking distance of an SUV equipped with tires made with compound two.

Its sample mean is X[bar]₂= 71 feet

And the Standard deviation S₂= 7.6 feet

We don't have any information on the distribution of the study variables, nor the sample data to test it, but since both sample sizes are large enough n₁ and n₂ ≥ 30 we can apply the central limit theorem and approximate the distribution of both variables sample means to normal.

The researcher's hypothesis, as mentioned before, is that the braking distance using compound one is less than the distance obtained using compound 2, symbolically: μ₁ < μ₂

The statistical hypotheses are:

H₀: μ₁ ≥ μ₂

H₁: μ₁ < μ₂

α: 0.05

The statistic to use to compare these two populations is a pooled Z test

$Z= \frac{(X[bar]_1-X[bar]_2)-(Mu_1-Mu_2)}{\sqrt{\frac{S^2_1}{n_1} +\frac{S^2_2}{n_2} } }$

Z ≈ N(0;1)

$Z_{H_0}= \frac{69-71-0}{\sqrt{\frac{108.16}{81} +\frac{57.76}{81} } }= -1.397$

The rejection region if this hypothesis test is one-tailed to the right, so you'll reject the null hypothesis to small values of the statistic. The critical value for this test is:

$Z_{\alpha } = Z_{0.05}= -1.648$

Decision rule:

If $Z_{H_0}$ > -1.648 , then you do not reject the null hypothesis.

If $Z_{H_0}$ ≤ -1.648 , then you reject the null hypothesis.

Since the statistic value is greater than the critical value, the decision is to not reject the null hypothesis.

At a 5% significance level, you can conclude that the average braking distance of SUV's equipped with tires manufactured used compound 1 is greater than the average braking distance of SUV's equipped with tires manufactured used compound 2.

I hope you have a SUPER day!

4 0

4 years ago

What does n^9/n^5 equal

vovangra [49]

Answer:

$n^4$