Ask question

Ask question

All categories

2 years ago

14

An elevator was at the 4" floor. It traveled up 18 floors, down 7 floors, up 6 floors and down 2 floors. What floor did the elev

ator end up on?

1 answer:

Gemiola [76]2 years ago

8 0

The answer is the 19th floor

You might be interested in

Time spent using e-mail per session is normally distributed, with mu equals 11 minutes and sigma equals 3 minutes. Assume that

liq [111]

Answer:

a) 0.259

b) 0.297

c) 0.497

Step-by-step explanation:

To solve this problem, it is important to know the normal probability distribution and the central limit theorem.

Normal probability distribution

Problems of normally distributed samples are 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 $\sigma$ , a large sample size can be approximated to a normal distribution with mean $\mu$ and standard deviation $s = \frac{\sigma}{\sqrt{n}}$

In this problem, we have that:

$\mu = 11, \sigma = 3$

a. If you select a random sample of 25 sessions, what is the probability that the sample mean is between 10.8 and 11.2 minutes?

Here we have that $n = 25, s = \frac{3}{\sqrt{25}} = 0.6$

This probability is the pvalue of Z when X = 11.2 subtracted by the pvalue of Z when X = 10.8.

X = 11.2

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

By the Central Limit Theorem

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

$Z = \frac{11.2 - 11}{0.6}$

$Z = 0.33$

$Z = 0.33$ has a pvalue of 0.6293.

X = 10.8

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

$Z = \frac{10.8 - 11}{0.6}$

$Z = -0.33$

$Z = -0.33$ has a pvalue of 0.3707.

0.6293 - 0.3707 = 0.2586

0.259 probability, rounded to three decimal places.

b. If you select a random sample of 25 sessions, what is the probability that the sample mean is between 10.5 and 11 minutes?

Subtraction of the pvalue of Z when X = 11 subtracted by the pvalue of Z when X = 10.5. So

X = 11

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

$Z = \frac{11 - 11}{0.6}$

$Z = 0$

$Z = 0$ has a pvalue of 0.5.

X = 10.5

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

$Z = \frac{10.5 - 11}{0.6}$

$Z = -0.83$

$Z = -0.83$ has a pvalue of 0.2033.

0.5 - 0.2033 = 0.2967

0.297, rounded to three decimal places.

c. If you select a random sample of 100 sessions, what is the probability that the sample mean is between 10.8 and 11.2 minutes?

Here we have that $n = 100, s = \frac{3}{\sqrt{100}} = 0.3$

This probability is the pvalue of Z when X = 11.2 subtracted by the pvalue of Z when X = 10.8.

X = 11.2

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

By the Central Limit Theorem

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

$Z = \frac{11.2 - 11}{0.3}$

$Z = 0.67$

$Z = 0.67$ has a pvalue of 0.7486.

X = 10.8

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

$Z = \frac{10.8 - 11}{0.3}$

$Z = -0.67$

$Z = -0.67$ has a pvalue of 0.2514.

0.7486 - 0.2514 = 0.4972

0.497, rounded to three decimal places.

5 0

3 years ago

Which lists the fractions 9/5, 13/8, and 1 and 3/5 in order from least to greatest?

aleksklad [387]

3/5, 1, 13/8, 9/5 this is the answer to your question

5 0

3 years ago

hey im qutting brainly so im gonna let you guys have the rest of my points im gonna have 61 left i have 161 rn but yeah here lol

marin [14]

Answer:

oof

Step-by-step explanation:

7 0

3 years ago

Solve for x. PLZ WAIT FOR THE PHTO TO UPLOAD

stepan [7]

6x² - 5x + -21 = 0

Because this whole equation equals zero, we must simply factorize the first half of the equation, or the left side.

(3x - 7)(2x + 3) = 0

I was never really taught a specific way to factorize, so I usually just guess and check when factorizing. It usually takes a long time, it always gives you the tight answer.

Then, take each equation and make it equal zero.

3x - 7 = 0 AND 2x + 3 = 0

3x - 7 = 0

Add 7 to both sides.

3x = 7

Divide both sides by 3.

x = 7/3

Now, we do our second equation.

2x + 3 = 0

Subtract 3 from both sides.

2x = -3

Divide both sides by 2.

x = -3/2

So, x = 7/3 AND x = -3/2

So, your answer is C) x = 7/3, x = -3/2

~Hope I helped!~

7 0

3 years ago

ANEK [815]

Answer:

Both lights would flash together after every 30 seconds.

Step-by-step explanation:

6 = 2 * 3 and 10 = 2 * 5.

LCM (Least Common Multiple) of 6 and 10 = 2 * 3 * 5 = 30.

Therefore, both lights wold flash together after every 30 seconds.

3 0

3 years ago