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1 year ago

Hiroto paid $4.28 in sales tax for the items that he purchased.

Mathematics

1 answer:

Katena32 [7]1 year ago

8 0

Answer:

$68.48

Step-by-step explanation:

You want to find cost such that ...

6.25% × cost = $4.28

Dividing by the coefficient of cost, we get ...

cost = $4.28/0.0625 = $68.48

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The time until recharge for a battery in a laptop computer under common conditions is normally distributed with mean of 265 minu

pochemuha

Answer:

a) 0.691 = 69.1% probability that a battery lasts more than four hours

b) 25% value = 231

75% value = 299

c) 183 minutes

Step-by-step explanation:

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.

In this problem, we have that:

$\mu = 265, \sigma = 50$

a) What is the probability that a battery lasts more than four hours?

4 hours = 4*60 = 240 minutes

This is 1 subtracted by the pvalue of Z when X = 240. So

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

$Z = \frac{240 - 265}{50}$

$Z = -0.5$

$Z = -0.5$ has a pvalue of 0.309

1 - 0.309 = 0.691

0.691 = 69.1% probability that a battery lasts more than four hours

b) What are the quartiles (the 25% and 75% values) of battery life?

25th percentile:

X when Z has a pvalue of 0.25. So X when Z = -0.675

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

$-0.675 = \frac{X - 265}{50}$

$X - 265 = -0.675*50$

$X = 231$

75th percentile:

X when Z has a pvalue of 0.75. So X when Z = 0.675

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

$0.675 = \frac{X - 265}{50}$

$X - 265 = 0.675*50$

$X = 299$

25% value = 231

75% value = 299

c) What value of life in minutes is exceeded with 95% probability?

The 100-95 = 5th percentile, which is the value of X when Z has a pvalue of 0.05. So X when Z = -1.645.

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

$-1.645 = \frac{X - 265}{50}$

$X - 265 = -1.645*50$

$X = 183$

8 0

2 years ago

Which transformation maps hexagon 1 into 3?

umka2103 [35]

Let's look at the possibilities:

1. Reflection along the y-axis and rotation of 180 degrees by the origin 0. (Gives us 4 and then 2 in the end)

2. Reflection along the y-axis and reflection along the x-axis. (Gives us 4 and then 3 in the end)

3. Reflection along the x-axis and rotation 90 degrees by the origin 0. (Gives us 4 and then 1 in the end)

4. Rotation of 270 degrees by the origin 0. (Gives us 2 in the end)

Option 2 is the answer.

Best of luck!

5 0

2 years ago

A botanist collected one leaf at random from each of 10 randomly selected mature maple trees of the same species. The mean and t

Zarrin [17]

Answer:

One sample t-test for population mean would be the most appropriate method.

Step-by-step explanation:

Following is the data which botanist collected and can use:

Sample mean
Sample Standard Deviation
Sample size (Which is 10)
Distribution is normal

We have to find the best approach to construct the confidence interval for one-sample population mean. Two tests are used for constructing the confidence interval for one-sample population mean. These are:

One-sample z test for population mean
One-sample t test for population mean

One sample z test is used when the distribution is normal and the population standard deviation is known to us. One sample t test is used when the distribution is normal, population standard deviation is unknown and sample standard deviation is known.

Considering the data botanist collected, One-sample t test would be the most appropriate method as we have all the required data for this test. Using any other test will result in flawed intervals and hence flawed conclusions.

Therefore, One-sample t-test for population mean would be the most appropriate method.

8 0

2 years ago

Malcolm has $638.54 in his checking account. He must maintain a $500 balance to avoid a fee. He wrote a check for $159.50 today.

e-lub [12.9K]

Your answer is c, 638.54 − 159.50 + x ≥ 500; x ≥ $20.96

5 0

2 years ago

Read 2 more answers

Let P2 be the vector space of all polynomials of degree 2 or less, and let H be the subspace spanned by 10x2+4xâ1, 3xâ4x2+3, and

lord [1]

I suppose

$H=\mathrm{span}\{10x^2+4x-1,3x-4x^2+3,5x^2+x-1\}$

The vectors that span $H$ form a basis for $P_2$ if they are (1) linearly independent and (2) any vector in $P_2$ can be expressed as a linear combination of those vectors (i.e. they span $P_2$ ).

Independence:

Compute the Wronskian determinant:

$\begin{vmatrix}10x^2+4x-1&3x-4x^2+3&5x^2+x-1\\20x+4&3-8x&10x+1\\20&-8&10\end{vmatrix}=-6\neq0$

The determinant is non-zero, so the vectors are linearly independent. For this reason, we also know the dimension of $H$ is 3.

Span:

Write an arbitrary vector in $P_2$ as $ax^2+bx+c$ . Then the given vectors span $P_2$ if there is always a choice of scalars $k_1,k_2,k_3$ such that

$k_1(10x^2+4x-1)+k_2(3x-4x^2+3)+k_3(5x^2+x-1)=ax^2+bx+c$

which is equivalent to the system

$\begin{bmatrix}10&-4&5\\4&3&1\\-1&3&-1\end{bmatrix}\begin{bmatrix}k_1\\k_2\\k_3\end{bmatrix}=\begin{bmatrix}a\\b\\c\end{bmatrix}$

The coefficient matrix is non-singular, so it has an inverse. Multiplying both sides by that inverse gives

$\begin{bmatrix}k_1\\k_2\\k_3\end{bmatrix}=\begin{bmatrix}-\dfrac{6a-11b+19c}3\\\dfrac{3a-5b+2c}3\\\dfrac{15a-26b+46c}3\end{bmatrix}$

so the vectors do span $P_2$ .

The vectors comprising $H$ form a basis for it because they are linearly independent.

4 0

2 years ago