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October 25, 2014

Posts by sarah


Total # Posts: 4,211

Logic
Situation 1: You have eight billiard balls. One of them is "defective," meaning that it weighs more than the others. How do you tell, using a balance, which ball is defective in two weighings? Situation 2: You have five jars of pills. All the pills in one jar only ...
January 21, 2013

structure and function of the human body
With your understanding of bone and muscle tissue (cells and the extracellular material) discuss two lifestyle factors (one for bone and one for muscle) that affect the growth, development, size and/or healing (positively or negatively) of the tissue. Also state whether the ...
January 20, 2013

calculus
limx→∞3x+127x+11
January 19, 2013

Math
An archer misses the target on her first shot and hits the target on the next 3 shots. What is the least number of consecutive shots that she must now make in order to have hit the target on at least 9/10 of all her shots? ( please show work on how to derive the answer!! Thx...
January 19, 2013

Math
At a college basketball game, the ratio of the number of freshmen who attended to the number of juniors who attended was 3 to 4. The ratio of the number of juniors who attended to the number of seniors who attended was 7 to 6. What was the ratio of the freshman to the number ...
January 19, 2013

physics
1 is angle 1 and 2 is angle 2
January 16, 2013

physics
Consider two vectors where F1 = 53 N, F2 = 81 N, 1 = 320 , and 2 = 13 ,measured from the positive x axis with the counter-clockwise. What is the magnitude of the resulting vector?
January 16, 2013

maths
A statistician wants to estimate the mean weekly family expenditure on clothes. He believes that the standard deviation of the weekly expenditure is $125. Determine with 99% confidence the number of families that must be sampled to estimate the mean weekly family expenditure ...
January 16, 2013

Math
Simplify. Express answer with positive exponents -48x^8y^-3/ 12x^-4y^6 Is x^12\4y^9
January 15, 2013

Math
Expand an simplfy. 3(x-6)(x+4)-(3x-5)^2 Is the answer -6x^2+24x-39
January 15, 2013

Liberal arts math
if this is the eaquation of a line y=2x+3 what is the parallel line and perpendicular line?
January 13, 2013

english
write a composition about whirlpools !
January 11, 2013

Social Studies
Examine The Black Family And Black Religion. Consider How Slavery Affected Both White And Black Views Of Women And Family.
January 9, 2013

Math
The sum of the integers from 40 to 60, inclusive, is 1050. what is the sum of the integers from 60 to 80 inclusive? Please help me find the pattern and how to use it instead of adding 60+61+62+63..... etc.
January 9, 2013

Math
The sum of the integers from 40 to 60, inclusive, is 1050. what is the sum of the integers from 60 to 80 inclusive? Please help me find the pattern and how to use it instead of adding 60+61+62+63..... etc.
January 9, 2013

MAth
what equation is that?
January 9, 2013

MAth
The front row of a stadium has 25 seats. Each of the other rows has two more seats than the row in front of it. how many seats are there altogether in the first 20 rows? i know how to do this in the "long" way but how do you do this is a "shorter" way by ...
January 9, 2013

calculus
three forces with magnitudes 100, 50, and 80 lb act on an object at angles of 50 degree, 160 degree, and -20 degree respectively. ind the direction and magnitude o the resultant force.
January 8, 2013

pre-cal
Three forces with magnitudxes 100, 50 and 80 lbs act on an object at angles of 50 degree, 160 degree and -20 degree respectively.
January 8, 2013

algebra 2
ok well sorry:P
December 31, 2012

algebra 2
Oh wait for the axis of symmetry put the vertex form to standard form and then do -b/2a For example: x^2+6x+13 A=1 B=6 C=13 Axis of Symmetry equation x=-b/2a x=-6/2(1) x=-3
December 31, 2012

algebra 2
vertex(6,-5) Direction is opening down(maximum) I don't know the axis of symmetry...but I hope this helped:)
December 31, 2012

AP Chemistry
How can you find the average temperature of a refrigerator or any fridge by using colligative properties?? I am doing a lab in school and i'm not sure how to approach or start this. I know that you have to have two solutions where on one solution, you put a tremendous ...
December 30, 2012

chemistry
sodium carbonate and hydrochloric acid react to give sodium chloride, carbon dioxide and water. How many grams of sodium carbonate and hydrochloric acid would be required to produce 286g of carbon dioxide? step by step answers please:)
December 29, 2012

Calculus-Regressions
How do you find the best and simplest model given a table of data? I know how to find a specific regression (linear, cubic ect...) but i'm lost when it comes to choosing the best one.
December 25, 2012

Chemistry
One of the flavouring compounds that have been isolated from aniseed oil is anethole. a.What is the configuration of the molecule, cis or trans? b. The compound will react with bromine. i.What would you observe? ii.Write an equation for the reaction.
December 19, 2012

math
help please! Factorise (x+4)(3x^2-11x+6)
December 19, 2012

Math
3.1 ft
December 16, 2012

Precalculus
log3 (x+1) - log3 (x-3) = 2
December 11, 2012

Precalculus
ln x -4 In 3 =ln (1/5 x)
December 11, 2012

Precalculus
More log/exponential equations log2 x + log2(x+2) =3
December 11, 2012

Precalculus
This is for solving exponential/logarithmic functions: (This is a base e Logarithmic function I would assume): e^(4x)/10 =4^x-2 ? I understand the properties of logs for the most part, but I have a hard time figuring out the step-by-step process on how to solve exponential/log...
December 11, 2012

Math
What is the simple interest on a loan with a principal of $6,000, an interest rate of 7.39%, and a term of four years?
December 11, 2012

CALCULUS
a bacteria culture grows with a constant per capita growth rate. After 2 hours there are 500 bacteria and after 6 hours the count is 312500, find the initial population and the population after 8 hours
December 9, 2012

math
a rectangular prism has l=6" & v= 144in^3. what are possible values for w & h?
December 7, 2012

Grade 11 MAth
Determine the equation of a sine function that would have a range of {y| -4 ≤ y ≤ 1, y ε R} and a period of 45o. Determine the cosine function that results in the same graph as the function above. Deter
December 7, 2012

Chemistry
How is the intercept of the Rydberg plot related to the Rydberg constant?
December 7, 2012

Chemistry Check
I just want to make sure I did the following problem right, and don't have to convert any further. What is the frequency of light whose frequency is 6.4 x 10^15 sec^-1? c= wavelength x v wavelength= c/v 3 x10^8 divided by 6.4 x 10^15 =4.69 x 10^-8?
December 7, 2012

Chemistry
The ionization energy of hydrogen is 1313 kJ/mol. Covert this energy to: wavelength (nm) 1/wavelength, reciprocal wavelength (cm^-1) spectral region? (IR, visible, UV, etc.) I know E=hv=hc/wavelength h=6.62 x 10^-34 J-s c= 3x10^8 v=c/wavelength But for some reason trying to ...
December 7, 2012

College Chemistry
Cu(s) + 4HNO3(aq) → Cu(NO3)2(aq) + 2H2O(l) + 2NO2(g) i need the chemical equation and the net ionic equation
December 6, 2012

PHYSICS
A force of 25.0 N acts at an angle of 25° to the horizontal. Find the horizontal and vertical components of the force.
December 5, 2012

Math
I have a 73.3 and that is worth 70% of my mark. My final is worth 30%. What do i need to get on my final to finish with anything over a 70%?
December 5, 2012

easy chemistry
what is the entropy of 10 molecules in a system of 100 boxes?
December 5, 2012

chemistry
what is the pH of the solution formed when 25 mL of 0.173 M NaOH is added to 35 mL of 0.342 M HCl?
December 5, 2012

chemistry
a buffer prepared by mixing equal moles of an acid having Ka=4.5x10^-4 and a salt of its conjugate base has a pH of what?
December 5, 2012

chemistry
the pH of a solution of HIO3 (Ka=1.7x10^-1) and KIO3 is 1.00. what is the molarity of KIO3 if the molarity of HIO3 is 0.025 M?
December 5, 2012

chemistry
what is the pH of the solution formed when 25 mL of 0.173 M NaOH is added to 35 mL of 0.342 M HCl?
December 5, 2012

chemistry
a buffer prepared by mixing equal moles of an acid having Ka=4.5x10^-4 and a salt of its conjugate base has a pH of what?
December 5, 2012

chemistry
the pH of a solution of HIO3 (Ka=1.7x10^-1) and KIO3 is 1.00. what is the molarity of KIO3 if the molarity of HIO3 is 0.025 M?
December 5, 2012

Physics- PLEASE HELP
The overall length of a piccolo is 30.6 cm. The resonating air column vibrates as in a pipe that is open at both ends. Assume the speed of sound is 343 m/s. (a) Find the frequency of the lowest note a piccolo can play, assuming the speed of sound in air is 343 m/s. (b) Opening...
December 4, 2012

Physics- PLEASE HELP
The overall length of a piccolo is 30.6 cm. The resonating air column vibrates as in a pipe that is open at both ends. Assume the speed of sound is 343 m/s. (a) Find the frequency of the lowest note a piccolo can play, assuming the speed of sound in air is 343 m/s. (b) Opening...
December 4, 2012

Physics- PLEASE HELP
The overall length of a piccolo is 30.6 cm. The resonating air column vibrates as in a pipe that is open at both ends. Assume the speed of sound is 343 m/s. (a) Find the frequency of the lowest note a piccolo can play, assuming the speed of sound in air is 343 m/s. (b) Opening...
December 4, 2012

Physics Please Help me!
The overall length of a piccolo is 30.6 cm. The resonating air column vibrates as in a pipe that is open at both ends. Assume the speed of sound is 343 m/s. (a) Find the frequency of the lowest note a piccolo can play, assuming the speed of sound in air is 343 m/s. (b) Opening...
December 4, 2012

Physics- Elena please help!
The overall length of a piccolo is 30.6 cm. The resonating air column vibrates as in a pipe that is open at both ends. Assume the speed of sound is 343 m/s. (a) Find the frequency of the lowest note a piccolo can play, assuming the speed of sound in air is 343 m/s. (b) Opening...
December 4, 2012

Algbra
Marsha must have surgery and she does not have the $2,700 cash necessary for the operation. Talking to an administrator at the hospital, she finds that it will accept MasterCard, VISA, and Discover credit cards. All of these credit cards have an APR of 13%, so she figures that...
December 4, 2012

Algbra
A car dealer will sell you the $16,650 car of your dreams for $3,290 down and payments of $331.97 per month for 48 months. What is the APR? (Round your answer to the nearest tenth of a percent.) I keep getting the wrong answer. I get 26.1
December 4, 2012

Trigonometry
Find all solutions between 0 and 2pi to tan(x)=-Squareroot3 exactly.
December 3, 2012

Physics
Two resistors of equal resistance are connected in series with each other and are connected to a battery that produces a potential difference of 8 V. If the current is 0.2 A what is the value of each resistance?
December 2, 2012

Chemistry
The compound CH3F has van der Waals constants a = 5.009 atm•L2 /mol 2 and b = 0.0562 L/mol. Using both the ideal gas law and van der Waals’s equation, calculate the pressure expected for 25 mol of CH3F gas in a 5.00-L container at 75 °C. no idea how to even start...
December 1, 2012

Chemistry
If you place 10.0 L of propanol (C3H8O) in a sealed room that is 7.5 m long, 3 m wide, and 3 m high, will all the propanol evaporate? If some liquid remains, how much will there be? The vapor pressure of propanol is 10.7 torr at 25 °C, and the density of the liquid at this...
December 1, 2012

Chemistry
Dimethylamine burns in oxygen according to the following equation: 4 C2H7N + 15 O2 → 8 CO2 + 14 H2O + 2 N2 (a) How many liters of O2 at 35 °C and 0.840 atm will be needed to burn 7.70 L of C2H7N at 35 °C and 0.840 atm? (b) How many liters of CO2 at 35 °C and ...
December 1, 2012

Chemistry
= 728/(2.807)(0.08206)(291.15) =10.855 g ?
December 1, 2012

Chemistry
What is the molar mass of a compound if a gaseous sample has a density of 2.807 g/L at 18 °C and 728 torr?
December 1, 2012

Physics !:(
A carbon dioxide laser is an infrared laser. A CO laser with a cavity length of 48.6cm oscillates in the m=100,000.0 mode. What is the wavelength of the laser beam? b). What is the frequency of the laser beam?
November 30, 2012

Calculus
Find the derivative of y = x^x
November 28, 2012

Calculus
Find the maximum volume of a cylindrical tin that has a total surface area of 600pi cm^2.
November 28, 2012

Math
I need help figuring out the unit rate for $5/3. Please help, :D
November 28, 2012

science
In cattle, red hair and white hair are codominant. Cattle with both white hair and red hair are what? please help! thanks!
November 27, 2012

Physics
1.6
November 27, 2012

Physics
A toy is attached to the cieling by a string. As the toy flies around in a horizontal circle with a radius 45 cm, the string makes an angle of 60 degrees with the cieling. What is the speed of the toy?
November 27, 2012

physics
Suppose the roller coaster in Fig. 6-41 (h1 = 34 m, h2 = 10 m, h3 = 30) passes point 1 with a speed of 1.60 m/s. If the average force of friction is equal to one fourth of its weight, with what speed will it reach point 2? The distance traveled is 60.0 m.
November 26, 2012

math 3rd grade
How can you use 4x7 to find 8x7? find the product. I dont understand this how can i expect my 3rd grader to understand.
November 26, 2012

Physics HELP!!
a). The displacement of a wave travelling in the positive x-direction is D(x,t)=(5.94cm)sin(1.18x-132.6t), where x is in meters and t is in seconds. What is the frequency? b). What is its wavelength? c).What is the speed of the wave?
November 24, 2012

physics ..PLEASE HELP ASSIGN DUE SOON :(
A jet airplane has an intensity of 97.7W/ m^2 when heard at a distance of 30.0m. What is the maximum sound intensity heard by a person on the ground when the airplane is 10100m overhead?
November 24, 2012

physics ..PLEASE HELP ASSIGN DUE SOON :(
A microphone has an area of 3.0cm^2. It receives during a 6.00s time period a sound energy of 1.0x10-11J. What is the intensity of the sound? b). Using the intensity in the previous question, what is the variation of pressure in the sound wave if the speed of sound is 343m/s ...
November 24, 2012

Spanish
whenever the word 'que' is used in a sentence and a verb follows it, the verb will always be in the unconjugated form. Tenemos que IR al parque. tienen que ESTUDIAR. tengo que HACER mi tarea.
November 21, 2012

Physics
For a certain transverse wave, the distance between two successive crests is 4.48m, and 13 crests pass a given point along the direction of travel every 5.97s. Calculate the wave speed!
November 21, 2012

Physics HELP!!
Earthquakes are essentially sound waves travelling through the earth. They are called seismic waves. Because the earth is solid, it can support both longitudinal and transverse sismic waves, which travel at different speeds. The speed of longitudinal waves, called P waves, is ...
November 21, 2012

Physical
It is experiment electric resistivty For the pencil line
November 20, 2012

Physical
The pencil line is made out of carbon atoms. Assuming that the average diameter of a carbon atom is 3.49x10^-10m, how many atoms thick is the pencil?
November 20, 2012

Physics
Football is kicked up into the air with a velocity of 20m/s. a. Determine the time the football is in the air. b. Determine the maximum height the football would reach. c. As the ball is kicked it encounters a weird horizontal wind that gives it a velocity of 5m/s. Determine ...
November 19, 2012

Physics
part 1 of 3: A hawk flies in a horizontal arc of radius 9.9 m at a constant speed of 4.8 m/s. Find its centripetal acceleration. Answer in units of m/s^2. part 2 of 3: It continues to fly along the same horizontal arc but increases its speed at the rate of 1 m/s^2. Find the ...
November 19, 2012

Physics URGENT!!!
A spring of negligible mass stretches 2.14 cm from its relaxed length when a force of 8.40 N is applied. A 1.300 kg particle rests on a frictionless horizontal surface and is attached to the free end of the spring. The particle is displaced from the origin to x=5.00 cm and ...
November 19, 2012

algebra
Find the cost of a home in 20 years, assuming an annual inflation rate of 5%, if the present value of the house is $260,000.
November 18, 2012

chemistry... HELP !!!!!!!
The average bond enthalpy for C__H is 413 kJ/mol. In other words, 413 kJ of energy is required to break a mole of CH into atoms: CH (g) ----> C(g) + H(g) delta H= 413 kJ Using this information, and enthalpy of C6H6=5535kJ, calculate the enthalpy change of the reaction: C6H6...
November 18, 2012

CHEMISTRY
Consider a 58.4 g sample of H2O(g) at 125°C. What phase or phases are present when -162 kJ of energy is removed from this sample? Specific heat capacities: ice, 2.1 J g-1 °C-1; liquid, 4.2 J g-1 °C-1; steam, 2.0 J g-1 °C-1, ΔHvap = 40.7 kJ/mol, ΔHfus...
November 17, 2012

CALCULUS
Find the length of the curve: y=ln(1-x^2), 0<_x<_1/2
November 16, 2012

CALCULUS
Let R be the region bounded by y=e^x, y=2. and the y-axis. Find the volume of the solid obtained by rotating the y-axis.
November 15, 2012

trig
given that 1/2pi<theta<pi and sin theta=1/5, use appropriate trigonometric formulas to find the exact values of the following (i) cos(2theta) (ii) cos theta (iii) sin(2theta)
November 15, 2012

PHYSICS
At what temperature would the rms speed of a nitrogen atom equal the following speeds? (Note: The mass of a nitrogen atom is 2.324 10-26 kg.) (a) the escape speed from Earth, 1.12 104 m/s _____K (b) the escape speed from the Moon, 2.37 103 m/s _____K
November 14, 2012

PHYSICS
An air bubble has a volume of 1.65 cm3 when it is released by a submarine 105 m below the surface of a lake. What is the volume of the bubble when it reaches the surface? Assume the temperature and the number of air molecules in the bubble remain constant during its ascent. ...
November 14, 2012

PHYSICS
One mole of oxygen gas is at a pressure of 5.25 atm and a temperature of 29.5°C. (a) If the gas is heated at constant volume until the pressure triples, what is the final temperature? ____°C (b) If the gas is heated so that both the pressure and volume are doubled, ...
November 14, 2012

PHYSICS
The average coefficient of volume expansion for carbon tetrachloride is 5.81 10-4 (°C)−1. If a 42.5-gal steel container is filled completely with carbon tetrachloride when the temperature is 10°C, how much will spill over when the temperature rises to 26.5°C...
November 14, 2012

PHYSICS
The Trans-Alaskan pipeline is 1300 km long, reaching from Prudhoe Bay to the port of Valdez, and is subject to temperatures ranging from -72°C to +38°C. (a) How much does the steel pipeline expand due to the difference in temperature? (The coefficient of linear ...
November 14, 2012

PHYSICS
Lead has a density of 1.13 104 kg/m3 at 0°C. (a) What is the density of lead at 86°C? ___kg/m3 (b) Based on your answer to part (a), now consider a situation in which you plan to invest in a gold bar. Would you be better off buying it on a warm day? Yes or No Explain.
November 14, 2012

Chemistry
What is the wavelength in Angstroms of radiation that has a frequency of 4.00 x 10^14 s-1? I tried the equation wavelength= constant / frequency. And the fact that 1 Angstrom = 1x 10^-10 m, but I don't see how the correct answer turns out to be 7.5 x 10^3
November 14, 2012

Chemistry
What is the energy in Joules of a mole of photons of microwave light having a frequency typical of microwave? (frequency = 3.0 x 10^9 Hz) I tried using the equation E= h x frequency, but I ended up with the answer 1.98 x 10^-24 instead of the correct answer 1.2 J, so there ...
November 14, 2012

Chemistry
What is the total volume of gases produced at 819 K and 1. atm pressure when 320 g of ammonium nitrite undergoes the following decomposition reaction? NH4NO2 --------> N2(g) + 2H2O(g)
November 14, 2012

Chemistry
Thanks so much, I would of never figured out that out myself past the empirical formula since I forgot about the 22.4L factor. The molar mass turns out to be 70, and since the only answer I was given that adds up to 70 is C5H10, it's an easy pick. Pentane!
November 14, 2012

Chemistry
An unknown gaseous hydrocarbon consists of 85.63% carbon by mass. A 0.335 g sample of the gas occupies a volume of 0.107 L at STP. What is the identity of the gas?
November 14, 2012

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