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musickatia [10]

2 years ago

5

Expression "-3x^2+y4x" when x = "-4" and y = 2 A. -112 B. -80 C. 80 D. 272

1 answer:

Paraphin [41]2 years ago

6 0

B, -3(-4)^2+(2)4(-4) plug into a calculator

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There are two college entrance exams that are often taken by students, Exam A and Exam B. The composite score on Exam A is appro

elena55 [62]

Answer:

B.The score on Exam A is better, because the percentile for the Exam A score is higher.

Step-by-step explanation:

Problems of normally distributed samples can be 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:

Two exams. The exam that you did score better is the one in which you had a higher zscore.

The composite score on Exam A is approximately normally distributed with mean 20.1 and standard deviation 5.1.

This means that $\mu = 20.1, \sigma = 5.1$ .

You scored 24 on Exam A. So

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

$Z = \frac{24 - 20.1}{5.1}$

$Z = 0.76$

The composite score on Exam B is approximately normally distributed with mean 1031 and standard deviation 215.

This means that $\mu = 1031, \sigma = 215$ .

You scored 1167 on Exam B, s:

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

$Z = \frac{1167 - 1031}{215}$

$Z = 0.632$

You had a better Z-score on exam A, so you did better on that exam.

The correct answer is:

B.The score on Exam A is better, because the percentile for the Exam A score is higher.

3 0

3 years ago

Find the product. Write your answer in<br> exponential form.<br> 6^-4•6^-9

Karolina [17]

Answer:

6^-13

Step-by-step explanation:

The rule for multiplying numbers with the same base but different exponents is a^b*a^c=a^(b+c), so in this case we have 6^(-4+(-9)) which is 6^-13

Hope this helped!

6 0

3 years ago

A scientist is growing bacteria in a lab for study. One particular type of bacteria grows at a rate of y=2t^2+3t+500. A differen

Leya [2.2K]

ANSWER

Approximately after 15 minutes.

EXPLANATION

The growth rate of the first bacteria is

$y = 2 {t}^{2} + 3t + 500$

The growth rate of the first bacteria :

$y = 3 {t}^{2} + t + 300$

To find the time that, there will be an equal number of bacteria, we equate the two equation;

$3 {t}^{2} + t + 300 = 2 {t}^{2} + 3t + 500$

$3 {t}^{2} - 2 {t}^{2} + t - 3t + 300 - 500 =00$

${t}^{2} - 2t - 200= 0$

We solve for t to get,

$t = 15.177$

Or

$t = - 13.177$

We discard the negative value.

This implies that,

$t \approx15$

8 0

3 years ago

A guy wire is needed to support a tower. The wire is attached from the top of the tower to a place on the ground 5m from the bas

worty [1.4K]

The wire is about 11.18 m long. This can be found using the Pythagorean theorem.

3 0

3 years ago

What’s 2 numbers that multiply to make -21 but add up to -4

irinina [24]

Answer:

2 numbers that multiply to make -21 = 3 x (-7)

2 numbers that add up to -4 = 3 - 7

Step-by-step explanation:

2 numbers that multiply to make -21 = 3 x (-7) = -21

2 numbers that add up to -4 = 3 - 7 = -4

4 0

2 years ago