Percy V.

Let X and Y be random variables with E(X)=3, E(Y) = 4, var(X)=2, var(Y) = 4 and cov(X,Y)=2.72. Define Z = -3+2X-1Y

What is the value of var(Z)?

Thx

If a telescope with excellent resolution could be used to monitor a protoplanetary disk about the same size as the one that became our solar system, how long would we have to wait between disk formation and the first planets of any kind?

Select one:

a.

About 1000 years.

b.

About 10 years.

c.

About 1 million years.

d.

About 100,000 years.

e.

Tens or hundreds of millions of years.

Thx

The orbit of Pan, a satellite of Saturn, lies within the Encke gap. Suppose a rock is orbiting within the gap at an orbital radius slightly smaller than that of Pan. Which one of the following is a correct description of the interaction between Pan and the rock?

a. The rock catches up to and passes Pan. As it does so Pan pulls itself forward, making it move faster and causing it to move into an orbit with a larger radius.

b. Pan catches up to and passes the rock. As it does so it pulls back on the rock, slowing it and causing it to move in an orbit with a smaller radius.

c. The rock catches up to and passes Pan. As it does so Pan pulls itself forward, making it move faster and causing it to move into an orbit with a smaller radius.

d. Pan catches up to and passes the rock. As it does so it pulls back on the rock, slowing it and causing it to move in an orbit with a larger radius.

a.

Sun formed initially, and the planets and major moons were captured much later as they drifted by the Sun.

b.

Sun contracted first as a gas ball, and the planets and moons formed shortly afterward by accretion and condensation.

c.

Sun formed first, the planets were spun off from the Sun, and the moons in turn were spun off from the planets.

d.

planets formed first out of the cold gas and dust nebula, followed by the Sun, which formed when the gas had become much hotter.

Thanks

The orbital period of Saturn is about 30 years. What is the time between our "top view" of its rings at maximum tilt and our next observation of this "top view"?

a. 60 years

b. The time depends on the difference in directions between Earth's rotation axis and Saturn's rotation axis.

c. 30 years

d. 15 years

Thanks

Two areas on the Moon have ages of 3.65 and 4.25 billion years, respectively. Based on this information, we expect that

a. both regions have roughly the same amount of cratering because they have approximately the same age.

b. the older region has far more craters than the younger region because of changes in the cratering rate over that time.

c. the older region has 16% more craters than the younger region because its age is 16% greater than that of the younger region.

d. the older region has fewer craters than the younger region because the cratering rate was lower at earlier times.

All of the following conditions except one appear to be necessary in order for a planet or satellite to produce a planet-wide magnetic field by the dynamo effect. Which is the exception?

a. an interior containing material that can conduct an electric current

b. a rotation axis that tilts only slightly with respect to the ecliptic

c. an interior that is at least partially liquid

d. relatively rapid rotation around its axis

Thanks

Should I buy current Macbook Air now or wait for the new one with retina display which according to rumours, it will come out early next year?

Is it worth waiting for the new one?

http://www.youtube.com/watch?v=BmA0bbZSDN4

and who are those musician, i can see Sarah Chang, Mischa Maisky, Renaud Capuçon, Gidon Kremer, in this video (I dont know the rest).

No silly answer please!!!

Is it a good thing to move around while playing piano. My professor said its a good thing to do a bit gesture coz its help you to have a further control over the beat and dynamic. While my best friend who doesn't have any knowledge of music said it's annoying. Any comment or idea?

พี่ที่ผมรู้จักจบ ป โท ผมก็ไม่รู้จะซื้ออะไรให้เลยซื้อน้ำหอมให้ (ค่อนข้างมีราคา) พี่เค้าก็รับไปไม่ได้พูดอะไร อีกประมาณสองสามวัน พี่แกเดินเข้ามาหาผมแล้วถามผม เห้ยเราคิดไรกับพี่ป่าววะ ผมก็ตอบป่าว พี่แกก็บอกผมว่า โบราณนะเค้าถือว่าให้น้ำหอมกัน หมายถึงเกลียดขี้หน้ากัน หน้าพี่เหม็นหรอ ผมก็งงมาก ก็ตอบไปป่าวๆพี่ ซื้อมาให้แสดงความยินดีไง พี่แกก็ยื่นเงินมาให้ผม แล้วบอกผม อะนี่เงินพี่ให้ แก้บน ผมแบบช๊อคมากเลยรับไป. คือยังไงอะเสียความรู้สึกมากๆ ที่งงที่สุดคือจริงหรอ ที่ให้น้ำหอมคือเกลียดขี้หน้าคนที่ให้ ใครรู้เรื่องพวกนี้ช่วยมาตอบที

Ok, it's almost 3:30 am and I am still awake. I have a major exam tmr at 9:30 in the morning. I've been trying to sleep for 2 hours. So I think I am just going to study till the morning. Is it ok not sleeping for one day?

I know that Chopin met Liszt and Schumann in person. But what about Mendelssohn?

I had economic exam today which everyone said it was really easy. But I think I didn't study enough so I think I might get like 60%. My school mark was quite bad either. So will this affect my ATAR? I'm so stressed and depressed right now. And if I do really well on my other subjects, would it help? Ps. I have 10 units

In 3009, King Warren of Australia suspects the Earls of Akaroa, Bairnsdale, Claremont, Darlinghurst, Erina and Frankstan are plotting a conspiracy against him. He questions each in private and they will tell him.

Akaroa: Frankston is loyal but Erina is a traitor.

Bairnsdale: Akaroa is loyal.

Claremont: Frankston is loyal but Brirnsdale is a traitor

Darlinghurst: Claremont is loyal but Bairnsdale is a traitor

Erina: Darlinghurst is a traitor.

Frankston: Akaroa is loyal.

Each traitors knows who the other traitors are but will always give false information, accusing loyalists of being traitors and vice versa. Each loyalist tells the truth as he knows it, so his information on traitors can be trusted, but he may be wrong about those he claims to be loyal.

How many traitors are?

And who are traitors?

Post WWII period - destruction of the Berlin Wall

not the song he plays at the beginning (Clair de lune)

Thanks

I need ideas for my history debating next week. Thanks heap

I'm doing a hypothetical assignment for my history class, many ideas would be much appreciated.

ตอนนี้ยังไม่ค่อยเจ็บเท่าไร เวลาเจ็บก็จะเจ็บเป็นช่วงๆ

พอดีอยากจะทราบว่าถ้าทิ้งไว้อีกสักเดือนจะเป็นอะไรหรือป่าวครับ เผอิญช่วงนี้มีสอบ ไม่อยากหยุดเรียน

แล้วอยากรู้ว่าหลังจากผ่าเสร็จแล้ว จะปวดประมาณกี่วันครับ