Saturday
August 23, 2014

# Posts by Erica

Total # Posts: 533

Differential Equations
If y(t) depends on what C is, then how this equation doesn't contradict the uniqueness theorem if it has many solutions?
January 31, 2013

Differential Equations
Consider the differential equation: dy/dt=y/t^2 a) Show that the constant function y1(t)=0 is a solution. b)Show that there are infinitely many other functions that satisfy the differential equation, that agree with this solution when t<=0, but that are nonzero when t>0...
January 31, 2013

Differential Equations (Another) Cont.
For the following initial value problem: dy/dt=1/((y+1)(t-2)) a)Find a formula for the solution. b) State the domain of definition of the solution. c) Describe what happens to the solution as it approaches the limit of its domain of definition. Why can't the solution be ...
January 31, 2013

Differential Equations
Consider the differential equation: dy/dt=y/t^2 a) Show that the constant function y1(t)=0 is a solution. b)Show that there are infinitely many other functions that satisfy the differential equation, that agree with this solution when t<=0, but that are nonzero when t>0...
January 31, 2013

Differential Equations
For the following initial value problem: dy/dt=1/((y+1)(t-2)) a)Find a formula for the solution. b) State the domain of definition of the solution. c) Describe what happens to the solution as it approaches the limit of its domain of definition. Why can't the solution be ...
January 31, 2013

Differential Equations
Consider the differential equation: dy/dt=y/t^2 a) Show that the constant function y1(t)=0 is a solution. b)Show that there are infinitely many other functions that satisfy the differential equation, that agree with this solution when t<=0, but that are nonzero when t>0...
January 31, 2013

science
19. The term chromatin refers to a. the color of certain cells b. chromosomal DNA c. the fluid within the nucleus d. ribosomal RNA
January 28, 2013

Math
The charges on a monthly water bill came to \$0.86 per cubic meter of water used, plus a service charge of \$4.49. Last month Jeremy's water bill came to \$69.85, how many cubic meters of water had he used?
January 25, 2013

Differential Equations
The velocity v of a freefalling skydiver is well modeled by the differential equation m*dv/dt=mg-kv^2 where m is the mass of the skydiver, g is the gravitational constant, and k is the drag coefficient determined by the position of the driver during the dive. (a)Find the ...
January 24, 2013

Differential Equations
Find the general solution of the differential equation specified. 1) dy/dt= 1/(ty+1+y+1) 2) dy/dx=sec y I got y(x)=arcsin(x) for the second one. I'm not sure what to do with the first one.
January 22, 2013

Consumer/Bus Math Sem 1 (Standard)
Pat worked 43 hours and received \$7.25 per hour for regular pay and time-and-a-half for all hours over 40 hours. What were her weekly earnings? \$22.83 \$322.63 \$269.75
December 18, 2012

how to find the scale factor when not given one HELP THIS IS MY MATH HOMEWORK & ITS DUE FIRDAY 4-12-13:-0
November 28, 2012

Math
A rocket is launched from ground level with an initial vertical velocity (v0) of 176 ft/s. After how many seconds will the rocket hit the ground? (Hint: h(t) = -16t2 + v0t + h0)
November 26, 2012

Statistics (urgent)
A beverage comopany uses a machine to automatically fill 1-liter bottles. Assume that the population of volumes is normally distributed. The company wants to estimate the mean volume of water to within 1 ML. Determine the minimum sample size required to construct a 95% ...
November 18, 2012

statistics
A survey of adults found that 35% say that their favorite sport is professional football. You randomly select 120 adults and ask them if their favorite sport is professional football. Find the probability that more than 30 people answer yes.
November 18, 2012

Physics HELP!!
Elena, why do you have a 13 & 23 beside F? Or is this just to distinguish between the two forces
October 16, 2012

physics
How much heat is necessary to change 500g of ice at-10 celsius to water at 20 celsius?
October 15, 2012

calculus
A fence 8 feet tall stands on level ground and runs parallel to a tall building. If the fence is 1 foot from the building, find the shortest ladder that will extend from the ground over the fence to the wall of the building.
October 11, 2012

Managarial Finance
"Stephenson Real Estate Company was founded 25 years ago by the current CEO, Robert Stephenson. The company purchases real estate, including land and buildings, and rents the property to tenants. The company has shown a profit every year for the past 18 years, and the ...
October 8, 2012

calculus derivative
find the derivative of: y=(x/(x+1))^3
October 8, 2012

calculus derivative HELP!
Find the derivative of: y=2sqrt(x)-(1/x)
October 8, 2012

FREE BODY DIAGRAM calculus
A car is traveling north towards an intersection at 60mph at the same time a truck is headed east toward the same intersection at 45mph. Find the rate of change of the distance between the car and truck when the car is 3 miles south of the intersection and the truck is 4 miles...
October 7, 2012

find the equation for the line tangent to the curve at the given point. y=((x^2)+1)/((x^2)-1) at (2, 5/3)
October 7, 2012

find derivative of: f(x)=e^2 I know that b/c e is a constant the answer is 0, but how do I show that in my work?
October 7, 2012

physics
To plot the potential energy, simply plug your givens into the equation U=(1/2)kx^2. You should get a parabola that goes to 0 in the center. To determine the turning points of the block, use the law of conservation of energy. You know that Ui+Ki = Uf+Kf since there is no ...
October 7, 2012

biology
I am doing a project on Eukarya, Bacteria and Viruses where I have to explain why they are different. I know of their structural and reproductive differences but I am not sure about their uses or funtions. Please help!!
September 25, 2012

math
exam rose from 20.8 to 21.1 what percent increase was this nearest to the tenth?
September 24, 2012

Chemistry
thank you so much for the explanation
September 18, 2012

Chemistry
I need help please I am so confused. How much dry solute would you take to prepare each of the following solutions from the dry solute and the solvent? I know the MM of KCl is 74.55 107g of 0.535m KCl
September 18, 2012

Chemistry
thank you so very much
September 17, 2012

Chemistry
To what volume should you dilute 43.5mL of a 4.20M KI solution so that 24.0mL of the diluted solution contains 2.80g of KI? Please if you can explain it to me I am so confused.
September 17, 2012

Chemistry
A sample of 2.00 mol O2 (assumed perfect) is originally confined in a 20.0L at 273K and 2.24 atm. it undergoes reversable adiabatic expansion until the volume has increased by a factor of 3. Calculate q, w, delta u, delta h, and delta t. Cv=7/2R and cp=5/2R
September 6, 2012

calculus
Find the limit if it exist lim t-->pi/3 (tan(t)/t)+1
September 6, 2012

calculus
Find a delta for any epsilon given: x^2+x-6/x+3 and x0=-3
September 6, 2012

chemistry
write a step by step procedure explaining how you will separate the sand, potassium chloride, and iron
September 6, 2012

math
what would the following equation be in vertex form. y=-9x squared+72x+81. I have tried for hours and i cannot figure it out
September 1, 2012

Physics
The left ventricle of the heart accelerates blood from rest to a velocity of + 29.8 cm/s. (a) If the displacement of the blood during the acceleration is + 2.68 cm, determine its acceleration (in cm/s2). (b) How much time does blood take to reach its final velocity?
August 31, 2012

math
all these numbers kind of confuse me. Im not sure what ^ means. Right now the only equation i have learned is y= a(x-s)(x-t)
August 31, 2012

math
the dome over a town hall has a parabolic shape. the dome measures 48 m across and rises 12m at the centre. A vertical column needs to be attached to the dome at a point that is 4m away from its rim. How tall is the dome at this point? Also, what is the equation that models ...
August 31, 2012

math
how would I measure a distance or object using right angled trig?
August 14, 2012

math
Select a real life object (tree flagpole ect) or distance that cannot be measured directly. Describe how to measure an object or distance by right-angled trigonometry using methods such as SOH CAH TOA or the pythogrorean theorem. Organize all the data you need and preform the ...
August 14, 2012

math
a popular tourist attraction in ottawa is the Peace tower, which rises from the Center Block of the Parliment buildings. Describe at least one method that you could use to estimate the height of the tower, including the measurments you would need to make. Include labelled ...
August 13, 2012

math
a popular tourist attraction in ottawa is the Peace tower, which rises from the Center Block of the Parliment buildings. Describe at least one method that you could use to estimate the height of the tower, including the measurments you would need to make. Include labelled ...
August 12, 2012

the reason the test questions and answers is up there because its all wrong answers on purpose for cheaters. when i first started i passed two test by myself. then the last three test try to cheat to use the answers and failed three test then retook them by myself and passed. ...
July 9, 2012

alg
An amplifier has an input power of 5 mW. The output power is 100 mW. What is the decibel gain to the nearest decibel?
June 28, 2012

algebra ll
9y2+4=12y how to solve this equation using the zero factor
June 27, 2012

Math
What is the image of A(4,4) under a reflection in the point P(4,-2)?
June 10, 2012

Math
Jack is married to Jill. Their son, Junior, asked each of them to reveal their ages. Junior’s parents decided to tell him, but in the form of a puzzle. Jack told Junior, “If you reverse the digits in my age, you get your mother’s age. Jill told her son, “...
May 29, 2012

Math
At Irv's Rental Shop, Irv rents all kinds of cycles: unicycles, tandem bikes, regular bikes, and even tricycles for little kids. He parks all the cycles in front of his shop with a helmet for each rider strapped to the cycles. This morning Irv counted 57 helmets and 115 ...
May 15, 2012

statistics
a mean score on a standardized test is 50 with a standard deviation of 10. What are the following: 1. what scores fall between -1 and +1 standard deviation? 2. what percent of all scores fall between -1 and +1 standard deviation? 3. what score falls at +2 standard deviations? ...
May 11, 2012

statistics
where is this formula located on excel?
May 11, 2012

statistics
a final exam in statistics has a mean of 73 with a standard deviation of 7.73. Assume that a random sample of 24 students is selected and the mean test score of the sample is computed. What percentage of sample means are less than 70?
May 11, 2012

Math
Tino conducted a survey of all the eighth graders in his school for his math project.  He asked each student how much he or she spent on school supplies at the beginning of the year (rounded to the nearest dollar).  He also calculated the average amount spent and ...
May 8, 2012

math 101
al flynn wants to buy a van that cost 16,000 with an interst charge of 2,000. Al figures he can afford a monhtly oayment of 700 per month, If there aew 24 equal payments required could al afford the van.
May 6, 2012

physics
This looked a little sloppy imo... Here's my example 1. Find most probably velocity of Krypton v = √[(2*8.314J/K*273K)/(0.083798 kg)] = 237.75 m/s Find the ratio of each velocity 205/237.75 = .8808 The average is .8851 207/237.75 = .8894 Find the ratio of change in ...
April 18, 2012

Math
Nico was stunned when he opened the mail. Here was a check for \$322.50! This was the interest he earned on his investment. One year ago Nico had been given \$5,000. His parents made him put it in the bank and save it for college, but they said he could keep the interest it ...
April 16, 2012

chem
Hey you guys how do you find the moles of .75g of He
April 16, 2012

Chemistry
How can you determine which colorless liquid is less dense?
April 6, 2012

physics
Could you elaborate on this?
April 6, 2012

Math
The population of humorville is 8,500 people. In this town, jokes travel fast. In one hour, each person who hears a joke tells three other people who have not heard it, and tells no one else. Last Friday, a visitor from out of town told the police chief a new joke at 10:00a.m...
March 19, 2012

Statistics
Suppose that people's heights (in centimeters) are normally distributed, with a mean of 165 and a standard deviation of 6. We find the heights of 100 people. (a) How many would you expect to be between 157 and 173 cm tall? (b) How many would you expect to be taller than ...
March 14, 2012

Math
thanks steve
March 13, 2012

Math
I snap my fingers now. in one second, i snap them again. I wait two seconds and snap them a third time. I wait four seconds before snapping them again. then i wait eight seconds, then sixteen, and the pattern continues on. the interval between snaps doubles each time How many ...
March 13, 2012

Chemistry
2NaOH+2Al+2H2O --> 2NaAlO2+3H2 here is the reaction. If i am trying to find the mass of hydrogen produced and i am trying to convert .95 moles Al to moles H, which number from the reaction do I use for H when converting from moles to moles? Do I 6 because that's the ...
March 9, 2012

Math
the design below grows each day, as shown. if the pattern continues to grow like this, how many tiles will there be in the design on the tenth day? on the fiftieth day? Day 1 1 tile Day 2 5 tiles Day 3 13 tiles
March 5, 2012

Algebra 2
On some tubes of caulking, the diameter of the circular nozzle opening can be adjusted to produce lines of varying thickness. The table shows the length l of caulking obtained from a tube when the nozzle opening has diameter d and cross-sectional area A. 48. Determine whether ...
March 3, 2012

math
Mr. Jaskson's lunch cost \$8.00 plus 8% sales tax. He tipped the server 15% of total bill after sales tax was added. How much did Mr. Jackson spend in all?
February 26, 2012

Physics
well that doesn't look readable. the answer should still be right but I'll rewrite how I did the math Cfs = mv^2/rFn = ((2πr/T)^2)/r(g) = (4(π^2)r)/g(T^2) Cfs = 4(π^2)(0.159 m) / (9.8 m/s^2)(1.50 s)^2 = 0.28467
February 20, 2012

Physics
Static Friction Coefficient = Cfs For of Static Friction = Fs Normal Force = Fn Centripetal Force = Fc mass = m radius = r speed = v period of time = T Fs = Cfs * Fn so Cfs = Fs/Fn Fc = Fs and since Fs = mv^2/r Cfs = Fs/Fn = mv^2/r*Fn v = 2πr/T and Fn = mg so.... mv^2 (2...
February 20, 2012

Probability
In a Cc x Cc crossing of peas, 5 offspring are of genotype CC, 12 are of genotype Cc, and 6 are of genotype cc. What is the probability of this event?
February 16, 2012

Chemistry
How many formula units of (NH4)3PO4 are present in 12.25 g of K3PO4? Please explain so I can do these in the future! Very confused.
February 15, 2012

Chemistry
February 15, 2012

Chemistry
If 2.44 moles of H2 are reacted with excess Cl2, how many moles of Hcl can be produced? Please explain.
February 15, 2012

Physics
Ultrasound with a frequency of 4.275 MHz can be used to produce images of the human body. If the speed of sound in the body is the same(1.79 km/s) as in salt water, what is the wavelength in the body?
February 6, 2012

algebra
February 6, 2012

English
What kind of clause would (when painters looked at rapidly moving horses.) would it be a adverb,adjective, or noun?
February 6, 2012

Physics
A car's initial velocity of 13.5 m/s accelerates at a rate of 1.9 m/s^2 for 6.2 s. Then, it accelerates at a rate of -1.2 m/s^2 until it stops. 1) What is the car's maximum speed? 2) What is the total time from the start of the first acceleration until the car is ...
February 1, 2012

Physics
A car is speeding at 33.4 m/s. A police car starts in pursuit from rest when the car is 100 m past the cruiser. At what rate must the cruiser accelerate to catch the speeder before the state line, 1.2 km away from the speeding car? Include all steps if possible please, so that...
February 1, 2012

English- Infinitive phrases
That website is very helpful! Thank you :) So, because there is no "to" would the infinitive phrase include the verb too? : "made him work hard"
January 29, 2012

English- Infinitive phrases
For this question, the directions say to name the TWO infinitive phrases in this sentence... His wish to succeed as an architect made him work hard. I know that "to succeed as an architect" would be one infinitive phrase, but there isn't another "to" ? ...
January 29, 2012

Probability
Assume that 20% of a very common insect species in your study area is parasitized. Assume that insects are parasitized independently of each other. If you collect 10 specimens of this species, what is the probability that no more than 2 specimens in your sample are parasitized...
January 27, 2012

Probability
A drug company claims that a new headache drug will bring instant relief in 90% of all cases. If a person is treated with a placebo, there is a 20% chance that the person will feel instant relief. In a clinical trial, half the subjects are treated with the new drug and the ...
January 27, 2012

Probability
A drawer contains six bags numbered 1-6, respectively. Bag i contains i blue balls and 2 green balls. You roll a fair die and then pick a ball out of the bag with the number shown on the die. What is the probability that the ball is blue? Thank you!
January 27, 2012

Probability
A screening test for a disease shows a positive test result in 95% of all cases when the disease is actually present and in 20% of all cases when it is not. When the test was administered to a large number of people, 21.5% of the results were positive. What is the prevalence ...
January 27, 2012

Probability
You toss a fair coin four times. Find the probability of no more than three heads given that at least one toss resulted in heads. Thank you very much!!
January 27, 2012

Geometry
The ratio of the side lengths of a triangle. Is 2:4:5 and the perimeter is 55 cm. What is the length of the shortest side?
January 25, 2012

Chemistry
would you multiple 500x0.20 and then divide the amount with 1.30
January 20, 2012

Chemistry
large dose of vitamin C are supposed to cure the common cold. One commercial over-the-counter product consists of 500-mg tablets that are 20% by weight vitamin C. How many tablets should one take for a 1.30g dose of vitamin C?
January 20, 2012

chemistry
As the temperature of a gaseous substance is decreased at constant pressure, it will undergo a series of physical changes. Which is the correct sequence of physical states that will be encountered? a.Liquid, solid, gas b.Gas, solid, liquid c.Solid, liquid, gas d.Gas, liquid, ...
January 20, 2012

chemistry
As the temperature of a gaseous substance is decreased at constant pressure, it will undergo a series of physical changes. Which is the correct sequence of physical states that will be encountered?
January 20, 2012

History
Discuss why England's North American colonial empire had outstripped those of her European rivals by the end of the seventeenth century?
January 18, 2012

Probability
Assume that P(A) = 0.4, P(B) = 0.4, and P(A∪B) = 0.7. Find P(A∩B) and P(A complement ∩ B complement).
January 17, 2012

Probability
In the game of poker, determine the number of ways a straight (five cards with consecutive values, such as A 2 3 4 5 or 7 8 9 10 J or 10 J Q K A, but not all of the same suit) can be picked.
January 17, 2012

Probability
Twelve children are divided up into three groups, of five, four, and three children, respectively. In how many ways can this be done if the order within each group is not important? Thank you so much!
January 17, 2012

Probability
Automated chemical synthesis of DNA has made it possible to custom-order moderate length DNA sequences from commercial suppliers. Assume that a single nucleotide weighs about 5.6 X 10^-22 grams and that there are four kinds of nucleotides. If you wish to order all possible DNA...
January 16, 2012

Algebra 2
From 1990 to 1994, the mail order sales of health products in the United States can be modeled by S = 10t 3 + 115t 2 + 25t + 2505 where S is the sales (in millions of dollars) and t is the number of years since 1990. In what year were about \$3885 million of health products ...
December 30, 2011

Algebra 2
Find the value of c that makes the expression a perfect square trinomial. Then write the expression as the square of a binomial. I didn't really understand what that meant. x^2-23x+c x^2-(2/7)x+c
December 5, 2011

Chemistry
a sample of gas has the pressure of 1120 mmhg and volume of 2.00 L. if the pressure is changed to 0.155 atm calculate the new volume
November 29, 2011

Calc
Describe in words the set of all points in R³ that satisfy the following expressions: a) z=0 b) z≥0 c) y≤0
November 7, 2011

s.s
I just took this exam and the answer is, in fact, cotton yarn.
November 2, 2011

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