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elena-14-01-66 [18.8K]
3 years ago
10

Plz help me with this

Mathematics
1 answer:
Jlenok [28]3 years ago
6 0

Answer:  \bold{b)\quad \dfrac{-\sqrt{13}-5}{4}}

<u>Step-by-step explanation:</u>

\dfrac{3}{\sqrt{13}-5}\bigg(\dfrac{\sqrt{13}+5}{\sqrt{13}+5}\bigg)\\\\\\=\dfrac{3(\sqrt{13}+5)}{13-25}\\\\\\=\dfrac{3(\sqrt{13}+5)}{-12}\\\\\\=\dfrac{\sqrt{13}+5}{-4}\\\\\\=\dfrac{-\sqrt{13}-5}{4}

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What is x equal to in this equation​
morpeh [17]

Answer:

5

Step-by-step explanation:

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5 0
3 years ago
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In a process that manufactures bearings, 90% of the bearings meet a thickness specification. A shipment contains 500 bearings. A
vredina [299]

Answer:

c) P(270≤x≤280)=0.572

d) P(x=280)=0.091

Step-by-step explanation:

The population of bearings have a proportion p=0.90 of satisfactory thickness.

The shipments will be treated as random samples, of size n=500, taken out of the population of bearings.

As the sample size is big, we will model the amount of satisfactory bearings per shipment as a normally distributed variable (if the sample was small, a binomial distirbution would be more precise and appropiate).

The mean of this distribution will be:

\mu_s=np=500*0.90=450

The standard deviation will be:

\sigma_s=\sqrt{np(1-p)}=\sqrt{500*0.90*0.10}=\sqrt{45}=6.7

We can calculate the probability that a shipment is acceptable (at least 440 bearings meet the specification) calculating the z-score for X=440 and then the probability of this z-score:

z=(x-\mu_s)/\sigma_s=(440-450)/6.7=-10/6.7=-1.49\\\\P(z>-1.49)=0.932

Now, we have to create a new sampling distribution for the shipments. The size is n=300 and p=0.932.

The mean of this sampling distribution is:

\mu=np=300*0.932=279.6

The standard deviation will be:

\sigma=\sqrt{np(1-p)}=\sqrt{300*0.932*0.068}=\sqrt{19}=4.36

c) The probability that between 270 and 280 out of 300 shipments are acceptable can be calculated with the z-score and using the continuity factor, as this is modeled as a continuos variable:

P(270\leq x\leq280)=P(269.5

d) The probability that 280 out of 300 shipments are acceptable can be calculated using again the continuity factor correction:

P(X=280)=P(279.5

8 0
3 years ago
I NEED help with my homework. I don’t get it
DIA [1.3K]
Help with what part I can help
7 0
3 years ago
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6 cm equals how many mm?​
olga nikolaevna [1]

Answer:

it's 60 mm

Step-by-step explanation:

hope this is useful! have a wonderful day and God Bless you !!!

7 0
3 years ago
The distance between two cities is ninety miles, and a woman drives from one city to the other at a rate of 45 mph. At what rate
Zinaida [17]
<span>The distance between two cities is ninety miles, and a woman drives from one city to the other at a rate of 45 mph. At what rate must she return if the total travel time is three hours and forty minutes?

1st leg DATA:
distance = 90 mi ; rate = 45 mph ; time = d/r = 2 hrs.
</span><span>2nd leg DATA:
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Ans: 54 mph</span>
5 0
3 years ago
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