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2 years ago

What is the first step in solving In(x - 1) = In6 - Inx for x?

Mathematics

1 answer:

kobusy [5.1K]2 years ago

8 0

Answer:

x=3

Step-by-step explanation:

In(x-1) = In(6) - In(x)

In(x-1) + In(x) = In(6)

In((x-1)x) = In(6)

In(x^2-x) = In(6)

x^2-x=6

x^2-x-6=0

x^2+2x-3x-6=0

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

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

x=3 because x=-2 need to be cancel out

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2 years ago

Suppose that the national average for the math portion of the College Board's SAT is 515. The College Board periodically rescale

nasty-shy [4]

Answer:

a) 16% of students have an SAT math score greater than 615.

b) 2.5% of students have an SAT math score greater than 715.

c) 34% of students have an SAT math score between 415 and 515.

d) $Z = 1.05$

e) $Z = -1.10$

Step-by-step explanation:

To solve this question, we have to understand the normal probability distribution and the empirical rule.

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.

Empirical rule

The Empirical Rule states that, for a normally distributed random variable:

68% of the measures are within 1 standard deviation of the mean.

95% of the measures are within 2 standard deviation of the mean.

99.7% of the measures are within 3 standard deviations of the mean.

In this problem, we have that:

$\mu = 515, \sigma = 100$

(a) What percentage of students have an SAT math score greater than 615?

615 is one standard deviation above the mean.

68% of the measures are within 1 standard deviation of the mean. The other 32% are more than 1 standard deviation from the mean. The normal probability distribution is symmetric. So of those 32%, 16% are more than 1 standard deviation above the mean and 16% more then 1 standard deviation below the mean.

So, 16% of students have an SAT math score greater than 615.

(b) What percentage of students have an SAT math score greater than 715?

715 is two standard deviations above the mean.

95% of the measures are within 2 standard deviations of the mean. The other 5% are more than 2 standard deviations from the mean. The normal probability distribution is symmetric. So of those 5%, 2.5% are more than 2 standard deviations above the mean and 2.5% more then 2 standard deviations below the mean.

So, 2.5% of students have an SAT math score greater than 715.

(c) What percentage of students have an SAT math score between 415 and 515?

415 is one standard deviation below the mean.

515 is the mean

68% of the measures are within 1 standard deviation of the mean. The normal probability distribution is symmetric, which means that of these 68%, 34% are within 1 standard deviation below the mean and the mean, and 34% are within the mean and 1 standard deviation above the mean.

So, 34% of students have an SAT math score between 415 and 515.

(d) What is the z-score for student with an SAT math score of 620?

We have that:

$\mu = 515, \sigma = 100$

This is Z when X = 620. So

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

$Z = \frac{620 - 515}{100}$

$Z = 1.05$

(e) What is the z-score for a student with an SAT math score of 405?

We have that:

$\mu = 515, \sigma = 100$

This is Z when X = 405. So

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

$Z = \frac{405 - 515}{100}$

$Z = -1.10$

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3 years ago

Help me answer this question about congruent triangles. 50 points available.

Anuta_ua [19.1K]

Answer:

Step-by-step explanation:

No these triangles are not congruent.

Left triangle

Shortest side = 6 cm

Longest side = 13 cm

3rd side = unknown but < 13

Right triangle

Shortest side = 6 cm

Longest side = unknown but > 13

3rd side = 13 cm

Although the shortest side of both triangles is 6 cm, the longest side of the left triangle is 13 cm, whereas the longest side of the right triangle is unknown but will be more than 13 cm.

We do not know if any of the angles are congruent. If they were congruent, we would expect to see this marked by the same angle line(s) on each triangle.

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2 years ago

Pls help me on this question :-

Nastasia [14]

Answer:

We conclude that the rule for the table in terms of x and y is:

y = 3x+2

Step-by-step explanation:

The table indicates that there is constant change in the x and y values, meaning the table represents the linear function the graph of which would be a straight line.

We know the slope-intercept form of the line equation

y = mx+b

where m is the slope and b is the y-intercept.

Taking two points

(-2, -4)

(-1, -1)

Finding the slope between (-2, -4) and (-1, -1)

$\mathrm{Slope}=\frac{y_2-y_1}{x_2-x_1}$

$\left(x_1,\:y_1\right)=\left(-2,\:-4\right),\:\left(x_2,\:y_2\right)=\left(-1,\:-1\right)$

$m=\frac{-1-\left(-4\right)}{-1-\left(-2\right)}$

$m=3$

We know that the y-intercept can be determined by setting x = 0 and finding the corresponding y-value.

Taking another point (0, 2) from the table.

It means at x = 0, y = 2.

Thus, the y-intercept b = 2

Using the slope-intercept form of the linear line function

y = mx+b

substituting m = 3 and b = 2

y = 3x+2

Therefore, we conclude that the rule for the table in terms of x and y is:

y = 3x+2

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3 years ago