Which values of c will cause the quadratic equation –x2 + 3x + c = 0 to have no real number solutions? Check all that apply.

2 answers:

4 0

A quadratic equation has no real number solutions than the discriminant is less than zero

D < 0

(b^2 -4ac) < 0

(9 -4(-1*c) < 0

(9+4c) < 0

4c < -9

c < -9/4

hope this will help you

Sophie [7]2 years ago

4 0

Which values of c will cause the quadratic equation –x2 + 3x + c = 0 to have no real number solutions? Check all that apply.

–5,-9/2

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Find x in the given figure if m∠AOC = 124°.

Nastasia [14]

Answer:

A) 8

Step-by-step explanation:

Add angles AOB and BOC to get angle AOC.

Since we know the value of AOC is 124 and AOB+BOC=AO

Then (8x+25)+(6x-13)=124.

Combine like terms to get 14x+12= 124.

Solve for x by subtracting 12 from 124, then divide the answer by 14.

3 0

2 years ago

The length of time that an auditor spends reviewing an invoice is approximately normally distributed with a mean of 600 seconds

Bumek [7]

Answer: 11.5%

Explanation:

Since 1 minute = 60 seconds, we multiply 12 minutes by 60 so that 12 minutes = 720 seconds. Thus, we're looking for a probability that the auditor will spend more than 720 seconds.

Now, we get the z-score for 720 seconds by the following formula:

$\text{z-score} = \frac{x - \mu}{\sigma}$

where

$t = \text{time for the auditor to finish his work } = 720 \text{ seconds}
\\ \mu = \text{average time for the auditor to finish his work } = 600 \text{ seconds}
\\ \sigma = \text{standard deviation } = 100 \text{ seconds}$

So, the z-score of 720 seconds is given by:

$\text{z-score} = \frac{x - \mu}{\sigma}
\\
\\ \text{z-score} = \frac{720 - 600}{100}
\\
\\ \boxed{\text{z-score} = 1.2}$

Let

t = time for the auditor to finish his work
z = z-score of time t

Since the time is normally distributed, the probability for t > 720 is the same as the probability for z > 1.2. In terms of equation:

$P(t \ \textgreater \ 720) 
\\ = P(z \ \textgreater \ 1.2)
\\ = 1 - P(z \leq 1.2)
\\ = 1 - 0.885
\\ \boxed{P(t \ \textgreater \ 720) = 0.115}$

Hence, there is 11.5% chance that the auditor will spend more than 12 minutes in an invoice.

8 0

2 years ago

A sales completion team, aiming to reduce the shipment time of urgent orders, studies the current process and finds that the cur

4vir4ik [10]

Answer:

$P(1$

And we can find this probability with thi difference:

$P(-2$

And in order to find these probabilities we can use tables for the normal standard distribution, excel or a calculator.

$P(-2$

So then we expect about 72.5% of the current shipment times between 1 and 5 days

Step-by-step explanation:

Previous concepts

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".

Solution to the problem

Let X the random variable that represent the current shipment time of a population, and for this case we know the distribution for X is given by:

$X \sim N(4,1.5)$