Sunday

November 23, 2014

November 23, 2014

Total # Posts: 19,402

**math (please check answer)**

probability of failure = 147/156 it has to be one or the other so 1 - 147/156 = 9/156 = 3/52 agree
*June 10, 2014*

**math**

a ar ar^2 ar^3 sum of first 4 = a (1-r^4)/(1-r) = 32.5 a r^3 = 3375 a r^3 = 3375 r = 15 a ( 1-r^2)(1+r^2) /(1-r) = 32.5 a (1+r)(1+r^2) = 32.5 a (16)(226) = 32.5 a = .0089878 about 1 cent :) ar = .1348 ar^2 =2.02 ar^3 = 30.33 about 30 dollars
*June 10, 2014*

**math**

alcohol removed = 1/10 liter first time = 1/10 (.9) liter second time = 1/10 (.9)(.9) third time .... =1/10 (.9)^6 seventh time so amount removed = .1 + .1*.9^1 +....1*.9^6 seven terms a = .1 sum removed = .1 (1-.9^7)/.1 = .478 so amount remaining = 1-.478 = .522
*June 10, 2014*

**Physics**

You are welcome.
*June 10, 2014*

**Physics**

110 km/hr = 110,000 m/3600 s = 30.6 m/s m g h = (1/2) m v^2 9.81 h = .5 (30.6)^2 h = 47.7 meters (b) loss of energy = m g (47.7-22) = 750(9.81)(25.7) = 189,000 Joules lost (c) work done = force in direction of motion * distance moved 189,000 = F (22/sin2.5) F = 375 N
*June 10, 2014*

**Math**

distance = speed * time 3.54 * 10^7 = 3*10^8 t t = 3.54/3 * 10^-1 t = 3.54 / 30 = 0.118 seconds
*June 10, 2014*

**math**

dp/dt = p/8 dp/p = .125 dt ln p = .125 t + c p = Po e^.125 t
*June 10, 2014*

**math**

1.08^10 = 2.16 2.16 * 10,000 = 21,589.25
*June 10, 2014*

**math**

a ar ar^2 ar^2 - a = 25 or a (r^2-1) = 25 ar^2 - ar = 15 or ar(r-1) = 15 [25/(r^2-1) ] r (r-1) = 15 r (r-1) /[ (r+1)(r-1) ] = 15/25 = 3/5 r/(r+1) = 3/5 5 r = 3 r + 3 2 r = 3 r = 3/2 = 1.5 then a r^2 - a = 25 1.25 a = 25 a = 20 so 20, 30, 45, .....
*June 10, 2014*

**Math**

You are welcome.
*June 10, 2014*

**Math**

2 = e^35 k ln 2 = 35 k k = .0198 so a = 1400 e^.0198*3*60 a = 1400 e^3.565 a = 49,475.2
*June 10, 2014*

**Physics**

area of loop = .02^2 = .0004 m^2 dB/dt = .044/.1 = .44 emf = A dB/dt = .0004 *.44 = 1.76 * 10^-4 = .00018 V
*June 10, 2014*

**Physics**

Seems to me they better repel each other so I agree with you.
*June 10, 2014*

**math (cant figure it out)**

11 numbers, 6 of which are even if you count 0 as even (there are evidently 10 spaces between numbers but 11 numbers) so 6/11 but the question is poorly worded.
*June 10, 2014*

**My Final Algebra 1 Question**

a. x must be greater than 0 (undefined for x = 0) so x = 0 is not in the domain (infinite number of teachers) y, must be greater than 2 so range is 2 to very large (for small cost per teacher.) If x is a dollar per teacher, then y = 202 which seems a reasonable upper limit. b...
*June 10, 2014*

**Physics**

I agree with 1/2
*June 10, 2014*

**math**

(a+b)/2 = 9 so a+b = 18 sqrt ( a b) = 3 sqrt 5 so a b = 9*5 = 45 well so b = 45/a and a + 45/a = 18 or a^2 - 18 a + 45 = 0 ( a-15)(a-3) = 0 a = 15 or 3 so one of them is 3 and one of them is 15
*June 10, 2014*

**HISTORY**

Lincoln issued the proclamation under his powers as commander in chief of the US military ass an act of war. He had no authority to remove property from people with whom we were not at war.
*June 10, 2014*

**math**

arithmetic mean = (10+40)/2 geometric mean = sqrt (10*40) = 20
*June 10, 2014*

**HISTORY**

From Wikipedia: In the mid and late 1840s, immigrants from Ireland and Germany streamed into the city, swelling the population of Philadelphia and its suburbs.[52] In Philadelphia, as the rich moved west of 7th Street, the poor moved into the upper class' former homes, ...
*June 10, 2014*

**math**

value = 1540 *(1/2)^(n/4) when n = 0, years, cost = 1540 for person 1 when n = 4 years, cost = 1540/2 for person 2 when n = 8, years, cost = 1540/4 for person 3 etc
*June 10, 2014*

**Maths**

Since it asks for depth wrt average, we do not need the 4 m average but only how much it departs from average at t = 0, d = -2 (low tide, 2 feet below average) d = -2 cos 2 pi t/T since T = 12 hours is given d = -2 cos (pi t/6)
*June 10, 2014*

**Algebra 1--Please, help me!**

(2x-20)(x+1) for example would be 2 x^2 - 18 x - 20 (2 x - 10)(x + 2) would be 2 x^2 - 6 x - 20 so 18 or 6 would work
*June 10, 2014*

**calculus**

(x+3)^2 = p (y-q) g = x + 7 when g = 0, x = A 0 = A + 7 A = -7 so A is 4 to the left of -3 therefore B is 4 to the right of -3 or at B = +1 so g = 7 at x = 0 so C = 7 A = (-7,0) B = (1,0) C = (0,7)
*June 10, 2014*

**Algebra 1-- Please, check my answers!**

As far as I know, yes
*June 10, 2014*

**Algebra 1-- Please, check my answers!**

Now wait a minute. Somewhere in your text book it says that if the denominator of a fraction is zero, that spot must be excluded from the domain of the function since the answer is undefined. Try dividing some number by zero on your calculator. Answer is "c". I had ...
*June 10, 2014*

**Algebra 1-- Please, check my answers!**

5. Which if the following is a true statement about the function y = 1/x? a. The domain is all real numbers. b. The range is all real numbers. c. The domain is all real numbers except 0. d. The range is all real numbers except 1. A: a? ============================= No, ...
*June 10, 2014*

**math**

Ah, two of us posted answers above.
*June 9, 2014*

**math**

change percent to decimal fraction by dividing by 100 so we mean .25 * 250 off 62.50 off 250 - 62.50 = $ 187.50 alternatively 100% - 25% = 75 % 75/100 = .75 .75 * 250 = $ 187.50 againg
*June 9, 2014*

**Algebra 1--Please, check my answer!**

When x = 6 (x-6) = 0 so y = 0 when x = 6 That is when it hits the x axis
*June 9, 2014*

**Algebra 1--Please, check my answer!**

If x = 6, bang if x = 6 bang so at ONE point x = 6 which is the vertex of the parabola. It just grazes the x axis and both roots are right there.
*June 9, 2014*

**Algebra II**

smallest = s biggest = b medium = m b = s + 90 m = s + 30 s + m + b = 180 s + s + 30 + s + 90 = 180 3 s = 60 etc.....
*June 9, 2014*

**Calculus**

yes
*June 9, 2014*

**Calculus**

See Baggins, Bilbo, "There and Back Again".
*June 9, 2014*

**Calculus**

Your velocity is zero at t = 3 !!!!! right in the middle of your range. It reversed direction midstream You calulated displacement (where it moved to which was nowhere) instead of how far it went (distance moved) do t = 0 to t = 3 then t = 3 to t = 6 add the ABSOLUTE VALUES
*June 9, 2014*

**physics**

How much energy should it have? m g h = 1.6 * 9.81 * 2.9 How much does it have? (1/2) m v^2 = (1/2) * 1.6 * (2.8)^2 so subtract
*June 9, 2014*

**math study guide**

1. no idea, do not have data 2. I get 8/20 = .40 3. again no data but in theory 3/4 4. 15/100 = 3/20 5. 20/100 = x/50 ??? Hey, are you just guessing or what?
*June 6, 2014*

**Science**

You are welcome.
*June 6, 2014*

**Science**

a) yes b) yes c) yes d) yes, traveling wave, air particles moving
*June 6, 2014*

**Math**

19 marbles p(first is purple) = 2/19 now 18 marbles, what is p(yellow) first p(yellow) = 5/18 so p(NOT yellow) = 13/18 p purple then not yellow) = 2/19 * 13/18
*June 6, 2014*

**Math**

p(not 5) = 5/6 then p(green) = 1/6 so 5/6 * 1/6 = 5/36
*June 6, 2014*

**Math**

Permutations of 7 items taken 3 at a time. The order matters so it is permutations, not combinations. Look at "ordered subsets" in the link: http://dwb4.unl.edu/Chem/CHEM869N/CHEM869NMats/Permutations.html 7! / (7-3)! = 7!/4! = 7*6*5 = 210
*June 6, 2014*

**Math**

There are four possible results A. Mike and Dave both miss B. Mike hit, Dave miss C. Dave hit, Mike miss D. both hit p mike hits = .6 so misses = .4 p dave hits = .3 so misses = .7 So p(A) = .4 * .7 p(B) = .6 * .7 p(C) = .3 * .4 p(D) = .6 * .3 We want p(A) + p(D) = .28 + .18...
*June 6, 2014*

**Math**

say 8/64 are red then probability of two red is 8/64 * 7/63 = 1/8 * 7/63 the next one is yellow, again same answer but now twice the probability so in the end 8 * 1/8 * 7/63 = 7/63
*June 6, 2014*

**Science**

or yes, yes :)
*June 6, 2014*

**Science**

35 * g = weight weight * distance raised = work in which is exactly the increase in potential energy
*June 6, 2014*

**Algebra ll**

You are welcome.
*June 6, 2014*

**Algebra ll**

(x - a)^2 + (y-b)^2 = r^2 for circle of radius r and center at (a,b)
*June 6, 2014*

**Math**

This is more fun every hour! Four ways now :)
*June 6, 2014*

**Math**

LOL !!!
*June 6, 2014*

**Math**

sketch a graph first If it goes through (0,4) and (2,4) I suspect that the center is on the line x = 1 (x-1)^2 + (y-b)^2 = r^2 when x = 0, y = 4 1 + (4-b)^2 = r^2 when x = 2, y = 4 1 + (4-b)^2 = r^2 again of course when x = -5, y = 0 36 + b^2 = r^2 so 1 +(4-b)^2 = b^2+36 1 + ...
*June 6, 2014*

**Science**

8.b yes 9.c Huh? 21/21 = 1 10.a I do not think so. She, not the wheelbarrow, supplied the work. If it weighed 35 N and she lifted it 2.5 meters, then D would be correct. The problem is poorly written. It is not clear if the force is in the direction of motion.
*June 6, 2014*

**physics**

PE = - G m Me/R where G = 6.67 * 10^-11 Look at change in potential energy at R = 6.38*10^6 and at 6.38*10^6 + .120 *10^6 meters I bet it would not be far off to use m g h where g = 9.81 m/s^2 :) because 120 km is not far compared to Rearth
*June 6, 2014*

**calc**

draw a sketch If the interval means from x = -1 to x = +2, then it is also from y = 2 to y = 8 As I read it then this base is a triangle with corners at (-1,8) (2,2) and (-1,2) The volume of the figure would then be 2 times the area of the base Area of base = (1/2) (3)(6) = 9 ...
*June 6, 2014*

**pre calc**

(x+5)^2 = 4 (y + 1/2) vertex at (-5, -1/2) so for the left half x is always less than (to the left of) -5 an y is above -1/2 I do not know what else to say
*June 6, 2014*

**physics**

F = m g = G M m /r^2 so g = G M/R^2 double m, double g double R , divide by 4 so 15.5 / 2
*June 6, 2014*

**Chemistry**

In a liter you have .1 mol of HCl .1 * (35.5 + 1) = 3.65 grams/liter so in half a liter you have 1.825 grams of HCl
*June 6, 2014*

**Math**

2(117) - 1 is not 2001
*June 6, 2014*

**Math**

1, 3 , 5 , 7 , 9 ....... first is 1 = 2 - 1 second is 3 = 4 - 1 third is 5 = 6 - 1 number (n) = 2 n - 1 number (117) = 2(117) - 1
*June 6, 2014*

**MULTIPLY. WRITE EACH PRODUCT IN SCIENTIFIC NOTATIO**

a^x * a^y = a(x+y) a^x / a^y = a^x * a^-y = a^(x-y)
*June 6, 2014*

**algebra**

-6x^2 + 7 x just to be sure you followed all that
*June 6, 2014*

**physics**

Fx * x = 40 cos 28 * 100 foot pounds
*June 6, 2014*

**Math**

p(not red) = 1 - p(red)
*June 6, 2014*

**Calculus**

2 W + L = 40 so L = 40 - 2 W A = W L = W (40 - 2 W) = 40 W - 2 W^2 dA/dW = 40 - 4 W W = 10 so yes
*June 6, 2014*

**mathematics**

dy/dx = 6 x^2 + 15 x^4 then y = 2 x^3 + 3 x^5 + c find c 7 = 2(8) + 3(32) + c 7 = 16 + 96 + c c = -105 so y = 2 x^3 + 3 x^5 - 105
*June 6, 2014*

**Calculus**

A = x^2 = (3t+1)^2 = 9 t^2 + 6 t + 1 dA/dt = 18 t + 6 when t = 2 dA/dt = 36 + 6 = 42
*June 6, 2014*

**algebra**

excuse me, typo like 2^2 * 2^3 = 2^5 = 32 which is also 4*8
*June 6, 2014*

**algebra**

x^(9-2) = x^7 because x^a * x^b = x^(a+b) like 2^2 * x^3 = 2^5 = 32 which is also 4*8
*June 6, 2014*

**physics**

680C = 273+680 = 953 K 220 C = 273 + 220 = 493 K e = (953-493)/953 = .483 IF and ONLY IF it is a Carnot cycle heat engine (maximum efficiency)
*June 6, 2014*

**math**

36/60 = 6/10 = 3/5
*June 5, 2014*

**science pls help asap!!!**

the A horizon is topsoil wind removes topsoil mostly by abrasion loess is soil settled from the wind often in the lee of an obstacle. I am not sure dunes need an obstacle.
*June 5, 2014*

**math**

A) correlation coefficient is between -1 and +1 , not 1.09 B) negative coefficient means that y is pretty well correlated with negative x. It is pretty much a straight line but with negative slope. like y = -5x + 3 http://www.dmstat1.com/res/TheCorrelationCoefficientDefined.html
*June 5, 2014*

**math**

You got three even numbers (4 , 2 and 6) out of eight tosses.
*June 5, 2014*

**math**

5! 120
*June 5, 2014*

**math**

4*6*3 = ?
*June 5, 2014*

**Physics**

Fx dx + Fy dy (-3 * 3.6) - (7.6 * -2) 4.4
*June 5, 2014*

**algebra**

You are welcome.
*June 5, 2014*

**algebra**

I did. It is not a straight line. answer is no
*June 5, 2014*

**algebra**

what is (25-17)/(2-1) ? 8 what is (1 - -7) /( -1 - -2) ? 8/1 = 8 humm looks like slope = 8 so far but what about (17 -8)/ (1 - 0) = 9 !!!!! oh my, not the same slope crash not on a straight line of constant slope
*June 5, 2014*

**algebra**

Oh ! 5*3^1 = 15 5*3^2 = 5*9 = 45 45* 3 = 135 135 * 3 = 405
*June 5, 2014*

**algebra**

nor do I unless you have a value for n
*June 5, 2014*

**algebra**

You are welcome :)
*June 5, 2014*

**algebra**

If x = 2 2 * 1^2 = 2*1 = 2
*June 5, 2014*

**Science**

Hey, in orbit there is no air around you and therefore no air pressure. You must maintain approximately atmospheric pressure inside if manned. If unmanned, you still must make sure nothing blows up when the outside pressure goes to zero. There is no nice layer of air to ...
*June 5, 2014*

**Science**

It sounds like you might have proposed a space mission as a class project or something and the question is asking why it should be funded and how it would work with other efforts.
*June 5, 2014*

**Science**

1200 * 15 Joules 2500 * 16 Joules work = Force component in direction of motion * distance moved. I wonder why you are asking. This should be in the first sentence of the first paragraph of your text on the subject.
*June 5, 2014*

**science 1 question!!!**

Number 1 is really an English comprehension question. Rivers generally run down valleys. therefore I am at a loss to understand why a valley glacier would spread out over a continent while a continental glacier would stick to a spot in the mountains.
*June 5, 2014*

**science**

Potential energy gain = m g h where h is the distance lifted
*June 5, 2014*

**physics**

I assume you mean in a centrifuge? If so Ac = v^2/R so g = v^2/R v = sqrt ( R g) = sqrt (9.81 R)
*June 5, 2014*

**Physics**

The loudness is the amount of power passing through a square meter of area surrounding the source. As you get further from a constant power source, the loudness decreases because the area of a sphere surrounding the source increases. ( You know that. As you get further from a ...
*June 5, 2014*

**physics**

get V from momentum (75 + 52) V = 75 (1.8) calculate V calculate (1/2) m V^2 friction force = .042 * m * g friction force * distance = (1/2) m V^2 or actually m cancels .042 g d = .5 V^2
*June 4, 2014*

**physics**

(1/2) m v^2 = (1/2) k x^2
*June 4, 2014*

**physics**

Hey, you have done several of these now. Try
*June 4, 2014*

**Math**

cost per unit = cpu = C(x) / x = 36,100/x + 100 +.01 x d cpu/dx = 0 at min = -36,100/x^2 + .01 .01 x^2 = 36,100 x^2 = 3,610,000 x = 1900 units now go back and get cpu = 36,100/1900 + 100 + .01(1900) = 2019
*June 4, 2014*

**Math**

2 dimensional with 3 or more sides side angle
*June 4, 2014*

**Physics**

k = 30 N/.2 m = 150 N/m PE of spring = (1/2) k x^2 = 75(.04)=3 Joules normal force = m g friction force = .4 m g work done against friction = .2 *.4 * mg = .08*.25*9.81 = .196 Joules so Ke left = 3 - .196 = 2.8 Joules (1/2) m v^2 = 2.8 calculate v
*June 4, 2014*

**Precalculus**

6 letters if start with A so 5 left c(5,3) = 10 10 more start with I so 20 total others similar
*June 4, 2014*

**Precalculus**

2a 9*10*10 = 900 2b 4 * 5 * 5 2c 9 * 1 * 10
*June 4, 2014*

**Precalculus**

c(20,5) = 20!/(5!*15!) = 20*19*18*17*16 /(5*4*3*2) = 15504
*June 4, 2014*

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