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3 years ago

Find the value of z and simplify completely.

Mathematics

1 answer:

Anna71 [15]3 years ago

3 0

Answer:

z = 6√2 = 8.49

Step-by-step explanation:

In this question, we are to find the value of the length z.

Mathematically, using Pythagoras’s theorem we can do this.

The Pythagoras’ theorem states that the square of the length of the hypotenuse equals the sum of the length of the squares of the two other sides.

Kindly note that the hypotenuse is the side that faces the angle 90

These are the points needed to solve for z

Using Pythagoras,

z^2 = y^2 + 4^2

z^2 = y^2 + 16 •••••••(i)

x^2 + z^2 = 20^2

x^2 + z^2 = 400 •••••••••(ii)

z^2 + 16^2 = x^2. ••••••••(iii)

Substitute iii into ii

z^2 + 16^2 + z^2 = 400

2z^2 + 256 = 400

2z^2 = 400-256

2z^2 = 144

z^2 = 72

z = √(72)

z = 6√2

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After a 16% increase the price of a pair of running shoes was $40.60. What was the old price of the shoes

Delvig [45]

Answer:

34.10

Step-by-step explanation:

Note:

16% = .16

Important:

What was the <u>old price</u> of the shoes

Solution:

40.60 x .16 = 6.946 [Round:6.50]

40.60-6.50= 34.10

Hence, the old price of the shoes is $34.10

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Power +, Inc. produces AA batteries used in remote-controlled toy cars. The mean life of these batteries follows the normal prob

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Answer:

a) By the Central Limit Theorem, it is approximately normal.

b) The standard error of the distribution of the sample mean is 1.8333.

c) 0.1379 = 13.79% of the samples will have a mean useful life of more than 38 hours.

d) 0.7939 = 79.39% of the samples will have a mean useful life greater than 34.5 hours

e) 0.656 = 65.6% of the samples will have a mean useful life between 34.5 and 38 hours

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 z-score 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 p-value, 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.

Mean of 36 hours and a standard deviation of 5.5 hours.

This means that $\mu = 36, \sigma = 5.5$

a. What can you say about the shape of the distribution of the sample mean?

By the Central Limit Theorem, it is approximately normal.

b. What is the standard error of the distribution of the sample mean? (Round your answer to 4 decimal places.)

Sample of 9 means that $n = 9$ . So

$s = \frac{\sigma}{\sqrt{n}} = \frac{5.5}{\sqrt{9}} = 1.8333$

The standard error of the distribution of the sample mean is 1.8333.

c. What proportion of the samples will have a mean useful life of more than 38 hours?

This is 1 subtracted by the pvalue of Z when X = 38. So

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

By the Central Limit Theorem

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

$Z = \frac{38 - 36}{1.8333}$

$Z = 1.09$

$Z = 1.09$ has a pvalue of 0.8621

1 - 0.8621 = 0.1379

0.1379 = 13.79% of the samples will have a mean useful life of more than 38 hours.

d. What proportion of the sample will have a mean useful life greater than 34.5 hours?

This is 1 subtracted by the pvalue of Z when X = 34.5. So

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

$Z = \frac{34.5 - 36}{1.8333}$

$Z = -0.82$

$Z = -0.82$ has a pvalue of 0.2061.

1 - 0.2061 = 0.7939

0.7939 = 79.39% of the samples will have a mean useful life greater than 34.5 hours.

e. What proportion of the sample will have a mean useful life between 34.5 and 38 hours?

pvalue of Z when X = 38 subtracted by the pvalue of Z when X = 34.5. So

0.8621 - 0.2061 = 0.656

0.656 = 65.6% of the samples will have a mean useful life between 34.5 and 38 hours

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3 years ago

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Morgarella [4.7K]

Answer:

m∠A = 91°

Step-by-step explanation:

∠A ≅ ∠B (Vertical Angle Theorem). This means that the two angles will have the same measurements.

Note that a straight line = 180° (Definition of a Straight Line).

Find the value of m∠B.

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