Homework Help

1. The problem statement, all variables and given/known data Determine which of the following protocols are insecure against replay attack , and explain why: (a) A → B : username, password (b) A → B : username, h(timestamp, password) © A → B : username, timestamp, h(password) (d) A → B : username, h(password), h(timestamp) I know a is insecure, b is secure but I am not certain about c and d. Off the cuff, in C it seems that h(password) can be replicated as its in the open, as can timestamp, but then if timestamp can be replicated so can h(timestamp). No? I guess my answer is that a,c and d are all insecure, so…

Can someone please help me find the minimum and maximum of the following equation: (3x^2 + 2xy + y^2)/(x^2 - 2xy + 3y^2) Please show work! Thanks!

Hey, been given a few questions, done most of them but have no idea how to even start this, I would go to a lecturer but I feel it needs doing before then. Question: A particular lottery has the following rules: - you choose 5 numbers, with no repeats, from 34 numbers. -you then choose an additional bonus number from 14 numbers. This step does not depend on how you choose the first numbers. -To win the jackpot, your first five numbers must match the first five numbers drawn from 34, in any order, AND your bonus number must match the one drawn from 14. If you wanted to be guaranteed to win this lottery jackpot, what is the minimum number of tickets …

Hello, I do not understand how to solve the following problem. Help is greatly appreciated! From Earth, we see the orbit of Jupiter's largest moon, Ganymede, almost edge-on. At some point an observer would see it disappear behind Jupiter (enter Jupiter's shadow) and at some later time re-emerge on the other side of Jupiter. How long does it take for Ganymede to enter (or re-emerge from) Jupiter's shadow? Assume that the shadow has a sharp edge. (Hint: draw a picture of Jupiter showing Ganymede in orbit around it. Use a perspective in which the orbit is seen "edge on." How long does it tale Ganymede to completely disappear from view as it moves behind Jupiter, o…

So basically I am trying to figure out the # of possible combinations of a 3-person committee from a total of 13 members. I used 13_C_3 and that gave me 286 which I think is correct. I am having trouble with the follow-up questions. First one is, how many of the 286 committees would a particular person, let's say John, be on ? I manually calculated (using a spreadsheet) that number to be 66. Is this correct ? Is there a mathematical expression I can use to calculate that ? Second, how many of the 286 committees would two particular people, let's say John OR Vanessa, be on ? I could expand me spreadsheet and by tedious, visual counting figure this out, but is…

My professor hasn't been very helpful and I need some help with this. You wish to perform a restriction digest in a 20 microliter volume. Your DNA is .60 micrograms/microliter and you wish to digest 6.0 micrograms. Your restriction enzyme is provided as 2U/microliter. What are the appropriate volumes of Water: 10x buffer: DNA: Restriction enzyme: I saw one of the professors watching movies on his computer during his office hours and he said, "read the lab manual" when I asked him for help. He wrote the lab manual, and did a pretty poor job. Can an…

The guy who typed up our lab manual did a pretty bad job. This is how he tried to explain transformation efficiency: # colonies/mL/microgram DNA I can't tell if he meant (# colonies)/(mL/microgram) or what...he didn't write out an example either. Anyway. Here's the problem: You need 8x 10E9 colonies. If you only have .0053 micrograms of DNA and you could only have maximum (I know it should be "a maximum", which just goes to show you how little he cares) of 1 mL of transformed cells. What efficiency would you need to get that many colonies? Could somebody please show me how to set up the equations for this? I also nee…

Does anybody know how to create a worksheet using the excel program with the decay constancy formula of A=Ao e -(0.693t/T1/2) ?

61H1 --> 2He4 + 21H1 41H1 + 21H1 --> 2He4 + 21H1 41H1 --> 2He4 Revered Members, First equation is given in my text book to explain fusion reaction. Now i attempted the second and third reaction. This is the fusion reaction happening in stellar energy. My doubt is , Can i cancel the 21H1 found in LHS and RHS of second equation to arrive at the third equation?

Can you, please help me with this problem? If these two operations are defined as follows. With these new definitions, is R3 a vector space? a) (x1, y1, z1)+(x2, y2, z2)=(x1 + x2 + 2, y1 + y2 + 2, z1 + z2 + 2) c(x, y, z)=(cx, cy, cz) b) (x1, y1, z1)+(x2, y2, z2)=(x1 + x2 + 4, y1 + y2 + 4, z1 + z2 + 4) c(x, y, z)=(cx + 4c – 4, cy + 4c – 4, cz + 4c – 4) Thanks!

So as told in discription my problem is functions and parabola calculations.. Everything else like trigonometry and so i find comparely easy to see trough... Do you have any good ways how i can memoryze function formulas and understand them just by looking at them or make them by given the amout of values... Plzz help me out herePs if you know any good websites dump them in as well

I am a 6th grade science teacher that has to give this question to my kids. I dont even know how to answer this question so I dont know how to teach it. Anybody with any genetics background that can help would be greatly appreciated. I am intentionally not giving the answer to see how some of you would answer it. Thanks. 15)A green bean plant has a genotype of Ttyy, what are the possible genetic combinations that could be present in a bean from this plant? A) Ty, ty B) TT, Tt, tt, yy C) Tt, yy D) Tt, yy, Ty, ty

Three blocks are connected by massless cords and rest on a frictionless horizontal surface. The blocks are pulled to the right. Mass m_1 = 2 m_2 = 3 m_3, with m_1 on the left and m_3 on the right. if the pulling force is equal to 90N, then the tension in the cord between m_1 and m_2 is... a) 49 b) 15 c) 100 d) 44 e) 85 I realize that because the back block (m_1) is being pulled, only it's mass is used in calculating the tension. But beyond that, I'm lost. :/

My homework says there are "3/4 as many teenagers as preteens". Does this mean, when x=teenagers and z=preteens, that 3x/4=z or x=3z/4? This is a word problem for linear equations. I have done it both ways, and the book supports the fact that the answer is x=3z/4 when I looked at the answer at the back of my textbook, but I thought it was 3x/4=z according to the word problem and the not intention of the writer, so I wanted to verify with you guys. I think I am wrong, so how do you analyze this kind of problem involving "as"?

Hey guys, first post ! A few Q's on momentum: When a rock is falling down, it gains velocity due to Fg. Does this contradict the law of momentum ? When your increase your kinetic energy by a factor of 2, then your momentum increases/decreases by a factor of ? A rubber bullet R and a metal bullet M of equal mass strike a target T, R bounces off, M penetrates, which has a greater impluse? Give an example of a collision in which the momentum a of system is not conserved and explain why in this case it was not. Thanks in advance!

I had to write a paper about psi in which we formulate questions and then answer them, using scholarly references as support. Can you guys read it and tell what you think? (2 pages, Time New Roman, double-space, size 12 font) psiPaper2.doc

I have been trying to do this for a while and have no idea how, all I was given was that line DB is the median of line AC, I need to find the are of the triangles ADB and DCB, thanks for any help you can

Question states: Oxygen and carbon dioxide crossing between blood and air in the lungs must pass through cells of which of the following types: CHOICE A: type I pneumocyte only CHOICE B: type I pneumocyte and endothelial cells So, it's a matter of if endothelial cells are included or not? I am very lost..

Chem 12, no laughing . . .. Given two ions in a solution we can calculate the Trial Ion Product. My question here is, if one ion is disproportionately greater than the other will precipitate always form around when the Qsp == the Ksp value? Is this linear behaviour? I am just not convinced of the whole idea here. It assumes that the saturation point is invariant given the concentrations of the individual ions. What I am having a problem with is if Ksp = [A] = (1)(1) = 1 and we have [A]=10000 and =.0001 we will have a precipitate because Qsp == Ksp. So where is anything less than .0001M we will not? I would assume with such disproportionate values we wo…

Hi, I was wondering what the data and error analysis was. This is my f!rst science fair project, so I'm pretty clueless.. Could anyone explain this to me?

My experiment tests lead in current beaches to see if there actually is if there are dangerous levels lead even though there are regulations for it. There are six holes, each 10 meters apart. Each hole is 6 inches deep. I have a lead testing kit to check if there is lead. Thanks!

I know it is a type of energy currency in cells, but I'm sure there's more to it than that. Could someone please explain to me exactly what it does? I couldn't find anything in my revision books or on the net.

A baby hamster kidney (BHK) cell has a surface area of 3,400 micrometres². Assume that the endocyte clathrin-coated pits account for 2% of this area and that the surface area of a single coated pit is the same of that of a 100nm diameter clathrin coated vesicle that will be formed from it. If the cell surface has 100,000 transferrin receptors, around 70% are localised within coated pits, work out the following: If a transferrin receptor has a cross-sectional area of 50 Angstroms X 100 angstroms (5x10nm), how many receptors could be accomodated in a 100nm clathrin-coated vesicle assuming that only 50% of the surface area can be occupied by proteins?

A sample of carbon dioxide gas is collected over water at 25 degrees Celsius. Vapor pressure of water (l)=23.8 mmHg. Th carbon dioxide and water occupy a volume of 1.80 L at a pressure of 783.0 mmHg. What mass of Carbon dioxide is present? I'm thinking you just use pv=nrt to solve this, and then convert moles into mass. I guess I'm just not sure what pressure to use to get an exact answer. Do you use the pressure of the CO2 only to calculate the number of moles you have? So 783 mmHg-23.8 mmHg = The pressure of CO2? Then take the number you get from that and plug it into pv=nrt? Or do I just use the pressure of 783 mmHg, making the info given abo…

Hi there, I'm wondering if you guys can help me out? I'm currently looking at turning effect, moments and couples, and need some questions that are a little different to the basic: "If the force is _____ distance from the pivot, what is the moment?" and "Use the principle of moments to show that the force is ____ N" I'm currently studying AS physics, and would like something a little out of the box. Some criteria follow: The question naturally has to be hinged or pivoted It must follow the Theory of Moments Units are optional It must be entertaining I have stopped using mock papers and the such because they are very limiting in the terms of entertainment is…