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3 years ago

Plsss answer everything you know I need the answer ASAP

Mathematics

2 answers:

Evgesh-ka [11]3 years ago

8 0

1. bobby would be 21 and chris 18.

tamaranim1 [39]3 years ago

8 0

1) Answers: Bobby = 22, Chris = 19

Explanation:

This year Last year

Bobby: 3 + x 3 + x - 1 = 2 + x

Chris: x x - 1

Bobby (last year) + Chris (last year) = sum (last year)

2 + x + x - 1 = 39

2 + 2x - 1 = 39

2x + 1 = 39

2x = 38

x = 19

Bobby (this year): 3 + x = 3 + 19 = 22

Chris (this year): x = 19

******************************************************************

2. Answers: Beth = 25, Celeste = 30

Explanation:

This year Next year

Beth: x - 5 x - 5 + 1 = x - 4

Celeste: x x + 1

Beth (next year) + Celeste (next year) = sum (next year)

x - 4 + x + 1 = 57

2x - 3 = 57

2x = 60

x = 30

Beth (this year): x - 5 = 30 - 5 = 25

Celeste: x = 30

******************************************************************

3. Answers: Donna = 38, brother = 50

Explanation:

This year in 2 years

Donna: x - 12 x - 12 + 2 and (x + 2)/2 + 14

brother: x x + 2

Donna (in 2 years) = Donna (in 2 years)

x - 10 = (x+2)/2 + 14

x - 24 = (x+2)/2

2x - 48 = x + 2

x = 50

Donna (this year): x - 12 = 50 - 12 = 38

brother: x = 50

******************************************************************

4. Answers: Freddie = 40, Elena = 8

Explanation:

This year in 4 years

Freddie: 5x 5x + 4 and 3(x + 4) + 8

Elena: x x + 4

Freddie (in 4 years) = Freddie (in 4 years)

5x + 4 = 3(x + 4) + 8

5x + 4 = 3x + 12 + 8

2x = 16

x = 8

Freddie: 5x = 5(8) = 40

Elena: x = 8

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3 years ago

D is between C and E, CD = x 2 , CE = 32-2x, and DE = 12x. Find CD, DE, and CE.

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Answer:

CD = 4
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Step-by-step explanation:

The segment addition theorem tells you ...

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3 years ago

Twice a number, decreased by nineteen

anzhelika [568]

2n-19 I think is the answer :3

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3 years ago

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Mila [183]

Answer:

63/80 and 7/4 * 9/20

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2 years ago

A Government company claims that an average light bulb lasts 270 days. A researcher randomly selects 18 bulbs for testing. The s

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31.92% probability that 18 randomly selected bulbs would have an average life of no more than 260 days

Step-by-step explanation:

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

Normal probability distribution

When the distribution is normal, we use 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.

For a proportion p in a sample of size n, the sampling distribution of the sample proportion will be approximately normal with mean $\mu = p$ and standard deviation $s = \sqrt{\frac{p(1-p)}{n}}$