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2 years ago

What is 7 to the power of 8 times seven to the power of -4

Mathematics

2 answers:

Shalnov [3]2 years ago

4 0

Remember
$(x^a)(x^b)=x^{a+b}$
so
$(7^8)(7^{-4})=7^{8-4}=7^4$

lora16 [44]2 years ago

3 0

I do not believe that a power can be negative so that confuses me also

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2 years ago

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2 years ago

A model of a statue has a scale to the actual statue of 1 inch : 8 inches. What percent of the actual statue's height is the mod

ArbitrLikvidat [17]

Answer:

6.25%

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3 years ago

A civil engineer is analyzing the compressive strength of concrete. Compressive strength is normally distributed with σ = 31.62

AysviL [449]

Answer:

A sample size of at least 737 specimens is required.

Step-by-step explanation:

We have that to find our $\alpha$ level, that is the subtraction of 1 by the confidence interval divided by 2. So:

$\alpha = \frac{1-0.99}{2} = 0.005$

Now, we have to find z in the Ztable as such z has a pvalue of $1-\alpha$ .

So it is z with a pvalue of $1-0.005 = 0.995$ , so $z = 2.575$

Now, find the width M as such

$M = z*\frac{\sigma}{\sqrt{n}}$

In which $\sigma$ is the standard deviation of the population and n is the size of the sample.

In this problem, we have that:

$M = 3, \sigma = 31.62$

So:

$M = z*\frac{\sigma}{\sqrt{n}}$

$3 = 2.575*\frac{31.62}{\sqrt{n}}$

$3\sqrt{n} = 81.4215$

$\sqrt{n} = 27.1405$

$n = 736.60$

A sample size of at least 737 specimens is required.

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3 years ago