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Aleonysh [2.5K]
3 years ago
8

If 2k, 5k-1 and 6k+2 are the first 3 terms of an arithmetic sequence, find k and the 8th term.

Mathematics
1 answer:
Simora [160]3 years ago
4 0
Consecutive terms in an arithmetic sequence differ by a constant d. So

5k-1=2k+d
6k+2=5k-1+d
\implies\begin{cases}3k-d=1\\k-d=-3\end{cases}\implies k=2,d=5

Denote the n-th term in the sequence by a_n. Now that a_1=2, we have

a_n=a_{n-1}+5=a_{n-2}+2\cdot5=\cdots=a_1+(n-1)\cdot5

which means

a_8=2+(8-1)\cdot5=37
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Which ordered pair is NOT a solution of y = 2x +1?
Phantasy [73]

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C. y=2x+1

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2 years ago
What is the solution to the system below? <br> 3x + y = 11<br> y = x + 3
alexgriva [62]

Answer:

x = 2

y = 5

Step-by-step explanation:

3x + y = 11 equation (1)

-x + y = 3 multiply this equation by -1

x - y = -3 equation (2)

by adding 2 equations

4x = 8

x = 2

by sub. in Equation (2)

2 - y = -3

y = 2+3

y = 5

5 0
3 years ago
CNNBC recently reported that the mean annual cost of auto insurance is 965 dollars. Assume the standard deviation is 113 dollars
velikii [3]

Answer:

P(939.6 < X < 972.5) = 0.6469

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 normal distributions 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 normally distributed random variable X, with mean \mu and standard deviation \sigma, the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean \mu and standard deviation s = \frac{\sigma}{\sqrt{n}}.

For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.

CNNBC recently reported that the mean annual cost of auto insurance is 965 dollars. Assume the standard deviation is 113 dollars.

This means that \mu = 965, \sigma = 113

Sample of 57:

This means that n = 57, s = \frac{113}{\sqrt{57}} = 14.97

Find the probability that a single randomly selected policy has a mean value between 939.6 and 972.5 dollars.

This is the pvalue of Z when X = 972.5 subtracted by the pvalue of Z when X = 939.6. So

X = 972.5

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

By the Central Limit Theorem

Z = \frac{X - \mu}{s}

Z = \frac{972.5 - 965}{14.97}

Z = 0.5

Z = 0.5 has a pvalue of 0.6915

X = 939.6

Z = \frac{X - \mu}{s}

Z = \frac{939.6 - 965}{14.97}

Z = -1.7

Z = -1.7 has a pvalue of 0.0446

0.6915 - 0.0446 = 0.6469

So

P(939.6 < X < 972.5) = 0.6469

3 0
2 years ago
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