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lapo4ka [179]
3 years ago
7

Using the following intervals for the scores on a 30-point quiz, how many x's would fall over the interval of 19-21 on a line pl

ot?
Scores: 21, 27, 20, 29, 23, 21, 21, 27, 26, 25

Intervals: 19-21, 22-24, 25-27, and 28-30

A.1

B.4
Mathematics
1 answer:
VikaD [51]3 years ago
7 0

Answer:

B. 4

Step-by-step explanation:

Interval: 19-21

Scores that are between 19 and 21 are underlined:

Scores in order: <u>20, 21, 21, 21</u>, 23, 25, 26, 27, 27, 29

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Information reference tables what is the solution set of the equation log4 (x2 + 3x) − log4 (x + 5) = 1?
faust18 [17]
Use this property of logarithms:

\log_b\left(\dfrac{x}{y}\right)=\log_b x-\log_b y

Your equation transforms into:

log_4\left(\dfrac{x^2+3x}{x+5}\right)=1

Now, you have to apply the definition of a logarithm to express the equation in exponential form:

\dfrac{x^2+3x}{x+5} = 4^1

In case you don't remember, this is the definition of a logarithm:

\log_b x = y \iff b^y = x

The log is the exponent (y) you have to raise the base (b) to in order to get the power (x).

Finally, solve the rational equation:

\dfrac{x^2+3x}{x+5} =4 \iff x^2+3x=4(x+5)
\iff x^2-x-20=0
\iff x=\dfrac{1\pm\sqrt{(-1)^2-4\cdot(-20)}}{2}= \left \{ {{5} \atop {-4}} \right.

The correct answer is d.
5 0
3 years ago
HELP!! Two mechanics worked on a car. The first mechanic worked for 20 hours, and the second mechanic worked for 5 hours. Togeth
joja [24]

Answer:

  • first mechanic: $105/hour
  • second mechanic: $55/hour

Step-by-step explanation:

Let r represent the rate charged by the first mechanic. Then 160-r is the rate charged by the second mechanic. The total of charges is ...

  20r +5(160-r) = 2375

  15r +800 = 2375 . . . . . . eliminate parentheses

  15r = 1575 . . . . . . . . . . . . subtract 800

  r = 105 . . . . . . . . . . . . . . . divide by 15. First mechanic's rate.

  160-r = 55 . . . . . Second mechanic's rate

The first mechanic charged $105 per hour; the second, $55 per hour.

7 0
3 years ago
Read 2 more answers
What is -6x - 10(x - 4)​
weeeeeb [17]
-16x+40 is the solution of this problem.
4 0
3 years ago
A parabola intersects the x-axis at x=3 and x=9 what is the x-coordinate of the parabola's vertex?
KiRa [710]

Here we are given the x intercepts at x=3 and x=9

So let us try to make quadratic equation for this using given information.

We have factors in the form (x-a)(x-b)

where a and b are x intercepts given to us.

So rewriting in factored form:

y=(x-3)(x-9)

Now let us simplify it:

y=x^{2}-12x+27

Let us find the vertex now,

For a quadratic equation of the form:

y=ax^{2}+bx+c

For x coordinate , we have the formula,

x=\frac{-b}{2a}

So using this formula for our equation,

x=\frac{-(-12)}{2(1)}

So x = 6

Answer: The x-coordinate of the parabola's vertex is 6.


7 0
3 years ago
Read 2 more answers
The output from a statistical computer program indicates that the mean and standard deviation of a data set consisting of 200 me
lesya [120]

Answer:

The limit that 97.5% of the data points will be above is $912.

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:

\mu = 1500, \sigma = 300

Find the limit that 97.5% of the data points will be above.

This is the value of X when Z has a pvalue of 1-0.975 = 0.025. So it is X when Z = -1.96.

So

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

-1.96 = \frac{X - 1500}{300}

X - 1500 = -1.96*300

X = 912

The limit that 97.5% of the data points will be above is $912.

6 0
3 years ago
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