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3 years ago

8

Spiral Review Overnight, the temperature decreased by 17 1/2 °F. If the temperature began at -3.6 °F, what is the current temper

ature?

1 answer:

Alex3 years ago

7 0

Answer: -21.1°F

Step-by-step explanation:

-3.6 - 17.5 = -21.1°F

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Complete the equation so that it has solutions of –5 and 7.<br> +<br> = 0

nekit [7.7K]

Answer:

the answer is - 2

Step-by-step explanation:

7-5=2-2=0

8 0

3 years ago

What product is positive ?

s344n2d4d5 [400]

<h3>Answer: Choice D</h3>

=======================================================

Explanation:

The long way to do this is to multiply all the fractions out by hand, or use a calculator to make shorter work of this.

The shortest way is to simply count how many negative signs each expression has.

The rule is: if there are an even number of negative signs, then the product will be positive. Otherwise, the product is negative.

For choice A, we have 3 negative signs. The result (whatever number it is) is negative. Choice B is a similar story. Choice C is also negative because we have 1 negative sign. Choices A through C have an odd number of negative signs.

Only choice D has an even number of negative signs. The two negatives multiply to cancel to a positive. The negative is like undoing the positive. So two negatives just undo each other. This is why the multiplied version of choice D will be some positive number.

Or you can think of it as opposites. If you are looking up (positive direction) and say "do the opposite" then you must look down (negative direction). Then if you say "do the opposite", then you must look back up in the positive direction.

5 0

4 years ago

Susan subscribed to a video game rental service. She pays the same amount for each video game she rents plus a monthly fee to su

podryga [215]

Answer:

C-$6.00 monthly fee and $1.25 per video game

Step-by-step explanation:

7 0

3 years ago

Read 2 more answers

What is the probability that a random person who tests positive for a certain blood disease actually has the disease, if we know

xeze [42]

Answer:

Step-by-step explanation:

Hello!

Any medical test used to detect certain sicknesses have several probabilities associated with their results.

Positive (test is +) ⇒ P(+)

True positive (test is + and the patient is sick) ⇒ P(+ ∩ S)

False-positive (test is + but the patient is healthy) ⇒P(+ ∩ H)

Negative (test is -) ⇒ P(-)

True negative (test is - and the patient is healthy) ⇒ P(- ∩ H)

False-negative (test is - but the patient is sick) ⇒ P(- ∩ S)

The sensibility of the test is defined as the capacity of the test to detect the sickness in sick patients (true positive rate).

⇒ P(+/S) =<u> P(+ ∩ S) </u>

P(S)

The specificity of the test is the capacity of the test to have a negative result when the patients are truly healthy (true negative rate)

⇒ P(-/H) =<u> P(- ∩ H) </u>

P(H)

For this particular blood disease the following probabilities are known:

1% of the population has the disease: P(S)= 0.01

95% of those who are sick, test positive for it: P(+/S)= 0.95 (sensibility of the test)

2% of those who don't have the disease, test positive for it: P(+/H)= 0.02

The probability of a person having the blood sickness given that the test was positive is:

P(S/+)= <u> P(+ ∩ S) </u>

P(+)

The first step you need to calculate the intersection between both events + and S, for that you will use the information about the sickness prevalence in the population and the sensibility of the test:

P(+/S) =<u> P(+ ∩ S) </u>

P(S)

P(+/S)* P(S) = P(+ ∩ S)

P(+ ∩ S) = 0.95*0.01= 0.0095

The second step is to calculate the probability of the test being positive:

P(+)= P(+ ∩ S) + P(+ ∩ H)

Now we know that 1% of the population has the blood sickness, wich means that 99% of the population doesn't have it, symbolically: P(H)= 0.99

Then you can clear the value of P(+ ∩ H):

P(+/H) =<u> P(+ ∩ H) </u>

P(H)

P(+/H)*P(H) = P(+ ∩ H)

P(+ ∩ H) = 0.02*0.99= 0.0198

Next you can calculate P(+):

P(+)= P(+ ∩ S) + P(+ ∩ H)= 0.0095 + 0.0198= 0.0293

Now you can calculate the asked probability:

P(S/+)= <u> P(+ ∩ S) </u> =<u> 0.0095 </u>= 0.32

P(+) 0.0293

I hope it helps!

6 0

3 years ago

Ellen is excited to learn how to ski. She went to White Peaks Mountain, rented a pair of skis for $45, and took 4 hours of group

Vikentia [17]

Answer:

x=30h

Step-by-step explanation:

First, you need to figure out how much she actually paid for lessons, so you need to subtract 45 from 165.

165-45=120

Now you know she paid 120 dollars in total for lessons.

You know she took four hours of lessons, so you divide 120 by 4.

120/4=30

It takes $30 an hour for lessons.

Now you can form an equation.

Since you know it takes $30 per hour of lessons, it will be 30h.

x is the full amount of money paid

You don't need to add 165-45 to your equation because not everyone will need to rent skis when they come to White Peaks.

Hope this helps!

6 0

3 years ago