Word problem Definition and 499 Threads

Homework Statement Any help would be greatly appreciated! I have to use matrices to figure these out. 1. A retired couple wishes to invest $150,000, diversifying the investment in three areas: a high-risk stock with an expected rate of return of 15%, a low risk stock with an expected rate...

Homework Statement A woman measures the angle of elevation of a mountaintop as 12.0°. After walking 0.80 km closer to the mountain on level ground, she finds the angle to be 14.0° (a) Draw a picture of the problem, neglecting the height of the woman's eyes above the ground. Hint: Use two...

Homework Statement An electron has an initial speed of 3.0 x10^5 m/s. It undergoes an acceleration of 8.0 x 10^14 m/s/s. (a) How long will it take to reach a speed of 5.4 x 10^5 m/s? (b) How far will it have traveled in this time? Homework Equations Rate x Time= Distance The...

Homework Statement If 1200 cm^2 of material is available to make a box with a square base and an open top, find the largest possible volume of the box. Homework Equations - Differentiation rules - Magic? The Attempt at a Solution First, I drew a square. I drew little squares in...

Homework Statement A person bails out of an airplane at an a;titude of 15,000 feet, falls freely for 35 seconds, then opens the parachute. How long will it take the person to reach the ground? Assume linear air resistance pV ft/s^2, paking p=.17 without the parachute and p=1.5 with the...

Homework Statement http://www.webassign.net/www20/symImages/2/1/9a952b874da3363f9e9d0b7744eaff.gif The velocity v of blood that flows in a blood vessel with radius R and length l at a distance r from the central axis is v(r), where P is the pressure difference between the ends of the vessel...

A bauxite ore 86.0 percent Al2O3 by weight. How many grams of the ore are required to produce 20.0 grams of aluminum metal? (Formula masses: Al2O3=102 & Al=27.0) A) 12.3g, B) 32.5g, C) 37.8g, D) 43.9g So this is how I did it on the test but got it marked wrong. I reasoned take 1/.86=1.16...

Homework Statement I'm not sure if I posted this in the right section, I apologize If I did anything wrong. I am stuck on part 15(b), so I just wrote my answer down for the parts I got right because I felt that it is relevant information. I posted question 14 because question 15 is just an...

Homework Statement (a) On a sunny afternoon in April, three physics students took a mirror and a screen to the roof of a building. They selected a distant building, and while one student held the mirror a second one adjusted the distance between the screen and the mirror in an attempt to form...

Homework Statement It took Bill 1.5 times as long to drive to work as it took him to drive home. If the trip was 60 miles in each direction, and the total drive time round trip was 3 1/3 hours, what was Bill's average speed in mph on the way to work? Homework Equations Needs to be...

I'm not sure what part of this problem is saying: Find the center of mass of a lamina in the shape of an isosceles right triangle with equal sides of length a if the density at any point is proportional to the square of the distance from the vertex opposite the hypotenuse. bold part! So...

Is the follow problem complete? The professor is notorious for giving problems without the complete information by mistake. A optical firm purchases glass for lenses, and it is known from past experience that the variance of the refractive index of this kind of glass is 1.26x10^-4. Since it...

Homework Statement Assume that the Earth is a sphere with circumference of 24,900 miles. a. Find the volume of the Earth north of latitude 45 degrees. (hint: integrate with respect to y) b. Find the volume of the Earth between the equator and latitude 45Homework Equations circle: x^2 + y^2...

Homework Statement An airline finds that if it prices a ticket at $200, it will sell 300 more tickets per day. It estimates that each $10 price reduction will result in 30 more tickets sold per day. Find the ticket price and number of tickets sold that will maximize the airline's revenue...

Hello, new here, first post. Just need some help with homework. Question One Homework Statement This norman window is made up of a semicircle and a rectangle. The total perimeter of the window is 16 cm. What is the maximum area? ** * * <<<...

The problem. A 2.50uF capacitor is charged to 857V and a 6.80uF capacitor is charged to 652V. These capacitors are then disconnected from their batteries. Next the positive plates are connected to each other and the negative plates are connected to each other. What will be the potential...

I was hoping someone could help me approach this problem. A 2.50uF capacitor is charged to 857V and a 6.80uF capacitor is charged to 652V. These capacitors are then disconnected from their batteries. Next the positive plates are connected to each other and the negative plates are connected...

hey guys, can anyone here help me with this problem? "Rocket A has positive velocity v(t) after being launched upward from an initial height of 0 feet at t=0 seconds. The velocity of the rocket is recorded for selected values of t over the interval 0 <(or = to) t <(or = to) 80 seconds, as shown...

A population of rabbits triples every month. Assume we start out with 100 rabbits. a. How many rabbits are there after 4 months b. How long until there are 50,000 rabbits? Homework Equations ... this is where I am running into the trouble... I'm really not sure how to create the...

Homework Statement The voltage V in a power cable varies sinusoidally with time t. At t = 1, the voltage is 12 volts. The voltage rises to its maximum level of 20 volts by t = 6. At t = 11, the voltage returns to 12 volts and then begins to fall. The minimum voltage is 4 volts. Homework...

Homework Statement An ant of negligible dimensions start at the origin (0,0) of the standard 2-dimensional rectangular coordinate system. The ant walks one unit right, then one-half unit up, then one-quarter unit left, then one-eighth unit down, etc. In each move, it always turn...

So I've been talking with some people about this problem, but I can't seem to find the answer, or even set it up! "A region in space, when viewed from 3 different views, looks like a circle, looks like a square and looks like a triangle. Describe this object. And then use multiple integration...

I'm having trouble understanding this word problem. A construction worker drops a bolt while woring on a high-rise building 320m above the ground. After t seconds, the bolt has fallen a distance of s metres, where s(t) = 320-5t^2, o < t < 8 a. Find the average velocity during the first...

This is a simple word problem that I just can't wrap my head around. The answers are 7 and 9: The sum of two numbers is 16, but the sum of their squares is 130. Find the numbers. I am supposed to use a quadratic equation as a means to solve the question, and all I need to do is to create...

Homework Statement Here is the word problem: A cup of coffee contains about 120 mg of caffeine, while the half life of the caffeine in an adult is about 3.5 hours. 1.) Suppose you ingest a cup of coffee every 6 hours. Obtain an expression for the amount of caffeine , A sub n...

Homework Statement The cost associated with storing x units of a certain product is given by the function C(x) = 0.8x^2 - 12.8x + 2600 where C is measured in dollars and x in hundreds of units. What is the minimum cost ? The Attempt at a Solution Umm, yea. I would attempt it but I have no...

A tank initially contains 60 gal of pure water. Brine (saltwater) containing 1lb of salt per gallon enters the tank at 2gal/min. and the (perfectly mixed) solution leaves the tank at 3 gal/min; thus the tank is empty after exactly 1 hr. a)Find the amount of salt in the tank after t minutes...

A 120gal tank initially contains 90lbs of salt dissolved in 90gal of water. Saltwater containing 2lb/gal of salt flows into the tank at the rate of 4gal/min, and the well stirred mixture flows out of the tank at the rate of 3gal/min. How much salt does the tank contain when it is full? Well...

Homework Statement A spherical raindrops evaporates at a rate proportional to its surface area. If its radius is 3mm, and 1 hour later has been reduced to 2mm, find an expresssion for the raduis of the raindrops at anytime. Homework Equations Volume = \frac{4}{3}\pi R^3 Area = 4\pi...

Hi everyone, i have a exam coming up for Physics and this question from the kinematic unit is really bothering me. I've tried many times but i have no idea how to solve it. Some help would be greatly appreciated, thanks. :smile: Homework Statement Question: Town A and Town B are 6.0 x 10^2...

Homework Statement the population of a town grows at a rate proportional to the population at any time. its initial population of 500 increases by 15% in 10 years. what will be the population in 30 years? Homework Equations my teacher sucks at teaching and i have no idea what on Earth...

never mind i got it :)

Hootenanny, I have uninstalled nexus skin...I guess it did contribute to the fact I couldn't use the site's template! Homework Statement Note: This problem comprises many parts, but I will just skip to the last one, since it's the one I'm struggling to answer! An economist producing x...

Greetings, On the board today in my calculus class, the teacher had a word problem that has stumped some other teacher, and wanted to see if we could figure it out (I realize this is the PREcalculus board, but I'm sure calculus isn't required to solve the problem). I don't remember it word...

The problem starts by saying that an aircraft is flying such that it's longitudnal axis always points towards the point (0,0). The plane itself starts at some point on the x-axis (say like (10,0)). The plane always has a constant airspeed, and experiences a constant wind blowing "north" We...

Can you please help me with this quadratic word problem? An airplane flies 520 km against the win and 680 kim with the wind in a total time of 4hr. The speed of the airplane in still air is 300kim/hr. What is the speed of the wind? Any suggestion is greatly appreciated!

Hi, I need help with this question At a publicity event, Ayida, a stuntperson, will jump out of a helicopter with a jetpack on her back. The jetpack allows her to achieve a net upward acceleration of 4.4m/s^2 for a single interval of maximun length 10s. Ayida wants to time the use of the...

1. the tangent to the curve xy=4 at a point P in the first quadrent meets the x-axis at A and the y-axsis at B. Prove that the area of triangle AOB, where O is the origin, is independant of the position P. y=4/x Find thd slope of the Tangent lim f(a+h)-f(a) /h lim 4/a+h - 4/a /h lim 4a - 4a...

Ive got an assignment of word problems and can't seem to figure this one out: A 6 Litre car radiator is 2 thirds full of water. How much of a 90% antifreeze solution (90% is alcohol by volume) must be added to it to make a 10% antifreeze solution in the radiator? I came up with the...

Ive got an assignment of word problems and can't seem to figure this one out: A 6 Litre car radiator is 2 thirds full of water. How much of a 90% antifreeze solution (90% is alcohol by volume) must be added to it to make a 10% antifreeze solution in the radiator? I came up with the...

An airplane is flying on a flight path that will take it directly over a radar tracking station. If (s) is decreasing at a rate of 400 miles per hour when s=10 miles, what is the speed of the plane? Can someone explain in indepth response including reasons why each steps were taken. Thank you!

Bickford traveled twice as fast as Shawn traveled. Thus, Bickford could travel the 320 miles to the reef in only 2 hours less than it took shawn to travel the 240-miles to Jane's house. Find the rates and times of both boys. Just having problems figuring out the formula and how to set it up...

Every year in the US each working American typically pays in taxes a percentage of his or her earnings (minus the stand deuction). Karen's 2005 taxes were calculated based on the formula T(x)= .22(x-6500). That year the standard deduction was $6,500 & her tax bracket paid 22%. Write the...

acceleration/velocity word problem help! The problem is: A hot air balloon is ascending straight up at a constant speed of 7.0 m/s. when the balloon is 12.0 m above the ground, a gun fires a pellet straight up from ground level with an initial speed of 30.0 m/s. Along the paths of the...

I'm taking high school physics right now, and we're doing kinematics in one dimension. Well I've been stuck on this word problem for days and stumbled across this forum on a google search. Thought maybe you could help. Anyway it is: --------------------------------------------------------------...

At time t hours after taking the cough suppressant hydrocodone bitartrate, the amount, A, in mg, remaining in the body is given by A = 10(0.82)t. (a) What was the intial amount taken? 10 mg (b) What percent of the drug leaves the body each hour? 18% (c) How much of the drug is...

I'm having trouble just figuring out how to set these problems up. Here is one of them. A jogger and a walker both cover a distance of 5 miles. The runner is traveling 1.5 times faster than the walker and finishes in 25 minutes less time. How fast is each going? I know it probably...

Hello, I would love to get help or a formula to help figure out my son's word problem he arrived with this afternoon for Homework on his first day back to school here in Georgia. The problems is: Tim ate 100 cookies in 5 days. Each day he ate 6 more than he did the day before. How many...

Two carts with masses of 4.3 kg and 3.2 kg move toward each other on a frictionless track with speeds of 5.8 m/s and 4.5 m/s, respec- tively. The carts stick together after colliding head-on. Find their final speed. Answer in units of m/s. I plugged in the numbers into this equation...

A hockey puck sliding on a frozen lake comes to rest after traveling 175m. If it's initial velocity is 1.0m/s, what is its acceleration if that acceleration is assumed constatnt? Answer in units of m/s^2 I first divided 175/1.9 to get 92.11s. I then put 1.9/92.11 to get 0.02063. But it's...