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3 years ago

7 is the mean proportional between 2 and a number. Find the number, show all work.

Mathematics

2 answers:

erastova [34]3 years ago

7 0

Answer:

24½

Step-by-step explanation:

7 = sqrt(x × 2)

7² = 2x

x = 49/2

Dmitry_Shevchenko [17]3 years ago

4 0

Answer:

Step-by-step explanation:

Follow me please for answering the question

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You are working in a primary care office. Flu season is starting. For the sake of public health, it is critical to diagnose peop

Aleksandr-060686 [28]

Answer:

E. 0.11

Step-by-step explanation:

We have these following probabilities:

A 10% probability that a person has the flu.

A 90% probability that a person does not have the flu, just a cold.

If a person has the flu, a 99% probability of having a runny nose.

If a person just has a cold, a 90% probability of having a runny nose.

This can be formulated as the following problem:

What is the probability of B happening, knowing that A has happened.

It can be calculated by the following formula

$P = \frac{P(B).P(A/B)}{P(A)}$

Where P(B) is the probability of B happening, P(A/B) is the probability of A happening knowing that B happened and P(A) is the probability of A happening.

In this problem, we have that:

What is the probability that a person has the flu, given that she has a runny nose?

P(B) is the probability that a person has the flu. So P(B) = 0.1.

P(A/B) is the probability that a person has a runny nose, given that she has the flu. So P(A/B) = 0.99.

P(A) is the probability that a person has a runny nose. It is 0.99 of 0.1 and 0.90 of 0.90. So

$P(A) = 0.99*0.1 + 0.9*0.9 = 0.909$

What is the probability that this person has the flu?

$P = \frac{P(B).P(A/B)}{P(A)} = \frac{0.1*0.99}{0.909} = 0.1089 = 0.11$

The correct answer is:

E. 0.11

5 0

3 years ago

Terry and Callie do word processing. For a certain prospectus Callie can prepare it two hours faster than Terry can. If they wor

Dahasolnce [82]

Time taken by jerry alone is 10.1 hours

Time taken by callie alone is 8.1 hours

Solution:

Given:- For a certain prospectus Callie can prepare it two hours faster than Terry can

Let the time taken by Terry be "a" hours

So, the time taken by Callie will be (a-2) hours

Hence, the efficiency of Callie and Terry per hour is $\frac{1}{a-2} \text { and } \frac{1}{a} \text { respectively }$

If they work together they can do the entire prospectus in five hours

$\text {So, } \frac{1}{a-2}+\frac{1}{a}=\frac{1}{5}$

On cross-multiplication we get,

$\frac{a+(a-2)}{(a-2) \times a}=\frac{1}{5}$

$\frac{2 a-2}{(a-2) \times a}=\frac{1}{5}$

On cross multiplication ,we get

$\begin{array}{l}{5 \times(2 a-2)=a \times(a-2)} \\\\ {10 a-10=a^{2}-2 a} \\\\ {a^{2}-2 a-10 a+10=0} \\\\ {a^{2}-12 a+10=0}\end{array}$

using quadratic formula:-

$x=\frac{-b \pm \sqrt{b^{2}-4 a c}}{2 a}$

$x=\frac{12 \pm \sqrt{144-40}}{2}$

$\begin{array}{l}{x=\frac{12 \pm \sqrt{144-40}}{2}} \\\\ {x=\frac{12 \pm \sqrt{104}}{2}} \\\\ {x=\frac{12 \pm 2 \sqrt{26}}{2}} \\\\ {x=6 \pm \sqrt{26}=6 \pm 5.1} \\\\ {x=10.1 \text { or } x=0.9}\end{array}$