Thę grades on a math midterm at Springer are roughly symmetric with u = 72 and 0 = 4.5.

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

A company that offers tubing trips down a river rents tubes for a person to use and "cooler" tubes to carry food and water. A gr

mestny [16]

Answer: the group rented 11 Person tubes and 4 cooler tubes

Step-by-step explanation:

There are two types of tubes, Person tube and cooler tube.

Let P represent number of Person tubes that the group rented.

Let C represent number of Cooler tubes that the group rented.

The group spends $270 to rent a total of 15 tubes and Person tube $20 Cooler tube $12.50. Two linear equations can be derived from the above information

P + C = 15 - - - - - - - 1

20P + 12.5C = 270 - - - -- - - 2

Substituting P = 15 - C into equation 2,

It becomes

20(15-C) + 12.5C = 270

300 - 20C + 12.5C = 270

- 20C + 12.5C = 270 -300

7.5C = - 30

C = 30/7.5 = 4

P = 15 - C

P = 15 - 4 = 11

7 0

3 years ago

Four members from a 50 person committee are to be randomly selected to serve as chairperson, vicechairperson, secretary, and tre

alexdok [17]

Answer:

So, exists 5527200 different leadership structures.

Step-by-step explanation:

We know that four members from a 50 person committee are to be randomly selected to serve as chairperson, vicechairperson, secretary, and treasurer. The first perosn to be selected is the chairperson, the second to be selected as vice chairperson, the third is secretary, and the fourth is treasurer.

Since the order of the people is important to us, we have the following:

50·49·48·47=5527200

So, exists 5527200 different leadership structures.

3 0

3 years ago

During a game of roulette, a wheel is spun and a ball drops randomly into one of the wheel's numbered compartments. then the pro

scoray [572]

The two events are independent of each other.

According to the question during a game of roulette, a wheel is spun and a ball drops randomly into one of the wheel's numbered compartments. The ball can drop in any one of the wheel's numbered compartments , there is no restriction on it.

Now, the process is repeated with another random spin. when the process is repeated the ball can drop in any one of the wheel's numbered compartments , there is no restriction on it. As the first spin does not affect the second spin, we can conclude that these two events are completely independent of each other.

To know more about independent events refer to the link:

brainly.com/question/1374659

#SPJ4

6 0

1 year ago

Simplify each expression. Are these expressions equivalent.

OverLord2011 [107]

Yes the expressions are equivalent

6 0

3 years ago