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3 years ago

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Allied Plumbing charges $45 per service call plus $30 per hour. Ajax Plumbing charges $60 per service call plus $25 per hour. Ho

w many hours would a service call have to last in order for the total cost of each company to be the same?

1 answer:

blagie [28]3 years ago

3 0

Answer:

that crazy bro wow so crazy

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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

Please help ASAP really need this

Aleonysh [2.5K]

Answer:

$21.79 + c \leq 25$

Joshua can spend up to 3.21 on a card.

Step-by-step explanation:

$21.79 + c \leq 25$ is the correct equation because Joshua is spending 21.79 on flowers, a certain amount on the card, and the maximum he can spend is 25. That is why you use the less than or equal to sign.

To solve, first subtract 21.79 from both sides to get: $c \leq 3.21$ . This means that Joshua can spend up to 3.21 on a card.

Hope it helps!

3 0

3 years ago

Helpppppppppp ASAP pls and thankyouu

natima [27]

Answer:

1. The graph of the inequality, y > -3·x - 2, created with MS Excel is attached showing the following characteristics;

Linear

Shade is above the line

2. The graph of the inequality, y ≤ │x│ - 3, created with MS Excel is attached showing the following characteristics

Linear

Shade is below the line

3. The graph of the inequality, y < x² - 4, created with MS Excel s attached showing the following characteristics;

Quadratic

Shade below the line

Step-by-step explanation:

8 0

3 years ago

I really need help please

anastassius [24]

9514 1404 393

Answer:

60

Step-by-step explanation:

The minimum number required is the least common multiple (LCM) of 15 and 4. The numbers 15 and 4 have no common factors, so their LCM is their product.

15×4 = 60 strands are required

6 0

2 years ago

Complete this statement: A polygon with all sides the same length is said to be ______.

il63 [147K]

The correct answer to this question is letter "B. equilateral." Complete this statement: A polygon with all sides the same length is said to be equilateral.

Equilateral means all sides are the same length, equiangular means all angles are the same degrees, and regular means both equiangular and equilateral. Convex means that the interior angles can have a maximum of 180 degrees each; no vertexes can point to the center.<span>
</span>

7 0

3 years ago

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