Have I been solving these equations correctly?

Mathematics

1 answer:

Tresset [83]3 years ago

4 0

14)

2(-3)² => 2(-3)(-3) => 2*9 = > 18

27+18-11 => 27 + 7 = > 34.

16)

$\bf p(x)=\cfrac{x^2-4}{2x+1}\implies p(-8)=\cfrac{(-8)^2-4}{2(-8)+1}\implies p(-8)=\cfrac{64-4}{-16+1} \\\\\\ p(-8)=\cfrac{60}{-15}\implies p(-8)=-4$

17)

$\bf h(x)=3\cdot 9^x\implies h(-2)=3\cdot 9^{-2}\implies h(-2)=3\cdot \cfrac{1}{9^2} \\\\\\ h(-2)=\cfrac{3}{9^2}\implies h(-2)=\cfrac{3}{81}\implies h(-2)=\cfrac{1}{27}$

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Step-by-step explanation:

Hello!

The variable of interest is:

X: number of daily text messages a high school girl sends.

This variable has a population standard deviation of 20 text messages.

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The is no information about the variable distribution, but since the sample is large enough, n ≥ 30, you can apply the Central Limit Theorem and approximate the distribution of the sample mean to normal:

X[bar]≈N(μ;δ²/n)

This way you can use an approximation of the standard normal to calculate the asked probabilities of the sample mean of daily text messages of high school girls:

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3 years ago

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