Which of the following decimals would be found between 5 and 5

<img src="https://tex.z-dn.net/?f=15%20x%5E%7B2%7D%20%2B14x-49%3D0" id="TexFormula1" title="15 x^{2} +14x-49=0" alt="15 x^{2} +1

Alex777 [14]

$15x^2+14x-49=0\\\\
Terms:\\
a=15\ \ \ \ b=14\ \ \ \ c=-49\\
Quadratic\ Formula:\\\\
x=\dfrac{-b\pm\sqrt{b^2-4ac}}{2a}\\\\
x=\dfrac{-14\pm\sqrt{196+2,940}}{30}\\\\
x=\dfrac{-14\pm\sqrt{3,136}}{30}\\\\
x=\dfrac{-14\pm56}{30}$

$Roots:\\\\
x'=\dfrac{-14+56}{30}\\\\
x'=\dfrac{42}{30}\\\\
x'=\dfrac{21}{15}\\\\
\boxed{x'=\dfrac{7}{5}}\\\\\\\\
x''=\dfrac{-14-56}{30}\\\\
x''=\dfrac{-70}{30}\\\\
\boxed{x''=\dfrac{-7}{3}}$

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3 years ago

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The operation manager at a tire manufacturing company believes that the mean mileage of a tire is 48,564 miles, with a standard

DerKrebs [107]

Answer:

0.0091 = 0.91% probability that the sample mean would be less than 48,101 miles in a sample of 281 tires if the manager is correct

Step-by-step explanation:

To solve this question, we need to understand the normal probability distribution and the central limit theorem.

Normal probability distribution:

Problems of normally distributed samples can be solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the zscore of a measure X is given by:

$Z = \frac{X - \mu}{\sigma}$

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

Central limit theorem:

The Central Limit Theorem estabilishes that, for a random variable X, with mean $\mu$ and standard deviation $\sigma$ , the sample means with size n of at least 30 can be approximated to a normal distribution with mean $\mu$ and standard deviation $s = \frac{\sigma}{\sqrt{n}}$