Friday
April 25, 2014

Posts by Damon


Total # Posts: 16,220

Algebra II
In other words you did one of 120 sequences that yield 7 successes out of 10 trials.

Algebra II
....but the probability of failure is not independent of the probability of success :)

Algebra II
binomial distribution p(sucess) = 12/15 = 4/5 = .8 1-p = 1/5 = .2 n = 10 k = 7 P(x=7) = C(10,7) * .8^7 * .2^3 C(10,7) = 10!/[ 7! (3!) ] = 10*9*8 / (3*2) = 80*9/6 = 120 so P = (120)(.8^7)(.2^3) = 0.201

geometry
100 = 4x^2 25 = x^2 x = 5 or -5 but if you really want to use formula x^2 + 0 x - 25 = 0 x = [ -0 +/- sqrt (0 + 100) ] / 2 x = +/- 10/2 x = +/- 5

math (matrix)
I assume you meant the determinant 24 x + 3 x^2 + 6 x + 10 - 9x = 25 3 x^2 + 21 x -15 = 0 x^2 + 7 x - 5 = 0 x =-7/2 +/- (1/2) sqrt(69) What a mess, assume you have a typo. To invert matrix use http://matrix.reshish.com/inverse.php

math
100 * (1/8)/ (8/12+3/12) = 100 * (1/8) / (11/12) = 100 * (3/24)(22/24) = 100 (3/22) = 13.6%

Calc III
not a valid transformation, zeros on diagonal check with http://www.wolframalpha.com/widgets/view.jsp?id=d6a52679e750c30e320a7094ec975598

math
pi D = 3.14159 * 13

math
1" = 50 miles IS 2" = 100 miles so if 2" is only 25 miles, we will need four times as long a sheet of paper. so 4

whoops, arithmetic error
t^2 - 2 t - 3 = -(1/5)(h) t^2 - 2 t = -h/5 + 3 t^2 - 2 t + 1 = -h/5 + 4 (t-1)^2 = -(1/5) (h - 20) so max height at one second of 20 meters

Math 10
that is a parabola (quadratic) 5 t^2 - 10 t - 15 = -h find the vertex by completing the square t^2 - 2 t - 7.5 = -(1/5)(h) t^2 - 2 t = -h/5 + 7.5 t^2 - 2 t + 1 = -h/5 + 8.5 (t-1)^2 = -(1/5) (h - 42.5) so max height at one second of 42.5 meters

math
r = 24 in /gift * 1 yd / 36 in * number of gifts r = (24/36) * number of gifts cost = 2 * r

math
10 apples/basket 2 baskets/bushel so 20 apples per bushel min 900/20 = 90/2 = 45

math
number of cuts = (n-1) amount wasted = 1/16 * (n-1) amount total = (3/32) n + (1/16) n - 1/16 so 25 16/32 = 5 n/32 -2/32 816/32 +2/32 = 5 n/32 818 = 5 n n = 163.6 so 163

free-body diagram help
You only need the horizontal forces in this case because the friction force(not the coefficient) is given. 45 - 13 = 20 a work done = change in kinetic energy = (45 - 13) (4) Newton meters or Joules

Physics
weight of ladder = m g = W force down on floor = W max friction force = .3 W so horizontal force on top of ladder from wall = . W Take moments about base of ladder .3 W (L sin T) = W(L/2)cos T .3 sin T = (1/2) cos T tan T = .5/.3 T = 59 degrees Notice that the ladder length do...

maths
1.875 km * 2 * 6 = 22.5 km

Maths
3 a = 4 2 a = -3 there is only one variable here, a there is no intersection of lines so no solution by elimination or substitution: a = 4/3 for the first equation a = -3/2 for the second equation

Math
Very interesting but as far as I know these are your apparel dimensions. I do not read minds and have no idea what you are looking at. Is it a triangle maybe?

math PLEASE HELP!!!!!
girth = 2(32+49) = 162 times length 41 = 6642 ft^2 base area = 32*41 = 1312 times height = 64288 ft^3 Why on earth do you need a formula? Draw a picture.

Circle Geometry
draw a picture line from center of circle to tack hits circumference at a right angle (because it is a radius) and therefore that is the closest point to the tack. also line from circle center to ground is 90 deg so right triangle d is hypotenuse center to tack r^2 + 58^2 = d^...

Calculus Help Please!!!
Q = Qi e^-k t when Q/Qi = 1/2 .5 = e^-k t ln .5 = - 4 k so k = (ln .5) / -4 Q = 800 e^ (ln .5)t / 4 k = .1733 so Q = 800 e^-.1733 t if t = 30 Q = 800 e^-5.2 Q = 4.4 mg 1/800 = e^-.1733 t ln(1/800) = -.1733 t 38.6 days enough already

Physics multiple choice questions
Ah, first you try and it is too late because I have to go to sailing practice. Maybe Steve will help.

Calculus Help Please
ln x y = lnx + ln y ln x + ln y -cos^-1(x-1) = x 1/x + (1/y) dy/dx+(1/[1-(x-1)^2])^.5 = 1 1/x +(1/y)dy/dx+(1/(-x^2+2x)^.5) = 1 (1/y) dy/dx = 1 - 1/x - [1/(x(2-x))^.5 dy/dx = y { 1 - 1/x - [1/(x(2-x))^.5 } when x = 1 ln x + ln y -cos^-1(x-1) = x 0 + ln y - pi/2 = 1 ln y = 1 + p...

Physics
east is + 1500 * 25 - 2000 * 0 = 3500 v

Physics
change in momentum of car A = 1250 (40) = 50,000 toward the west so change in momentum of car B is 50,000 toward the east 50,000 = 2000 (east velocity - -25) 25 = east velocity + 25 east velocity = 0 stopped it dead in the water :)

physics
change in temp = 90 - 15 = 75 deg C heat in = mass * specific heat * change in temp = 12 kg * specific heat * 75 deg C I do not know specific heat in Joules or calories or kilocalories or whatever you are using in your class / kilogram deg C

college alg.
Different initial up speed but use : http://www.jiskha.com/display.cgi?id=1396965991#1396965991.1396967805

college algebra
h = hi + Vi t - (1/2) g t^2 in ancient English units this is h = Hi + Vi t - (1/2) 32 t^2 If Hi = 0 Vi = 128 ft/s then h = 128 t - 16 t^2 for h = 144 144 = 128 t - 16 t^2 16 t^2 - 128 t + 144 = 0 t^2 - 8 t + 9 = 0 t = [ 8 +/- sqrt(64 -36) ]/2 t = 4 +/- sqrt 7 t = 1.35 t = 6.65

Calculus Help
y = sin [ pi*(t^2+5)^-.5 ] y' = pi [cos pi*(t^2+5)^-.5] * [-.5(2t)](t^2+5)^-1.5 if t = 2 y' = pi {cos pi/ 3} *[-2] [ 1/27 ] = -(2pi/27) cos (pi/3) but cos pi/3 = 1/2 so -pi/27 CHECK MY ARITHMETIC !!!! =

Calculus Help Please!!!
sin 2 x ---- 2 x + .... as x -->0 tan x also ---> x so 2x /(2x - x) 2x/x = 2

Math
least common multiple 8 = 2*2*2 30 = 5*2*3 so we need a 5, 3 twos, and a 3 so 120

math word problem PLEASE HELP
r = ribbon = 15 (5 3/8) - 10(3/4) r = 15 (43/8) - 60/8 r = (15*43 - 60 )/8 = 585/8 = 73 1/8 yards

Physics
Or approximate in your head 1 atm = 10^5 Pascals approx so 2.38 atm = about 2.3 *10^5 pascals which is 2.3 * 10^2 kilopascals or 230

Physics
use Google type 2.38 atm = Pascal get 2.38 atm = 241 153.5 pascals which is 241 Kilopascals

Physic II
300 g = .3 kg so .3 * .11 * 5 thousand calories

chemistry
.75 * .5 = .375 mols of Na2CO3 2 HCl + Na2CO3 --> 2 NaCl + H2O +CO2 so we need .375 * 2 = .75 mols of HCl .75 * 1.25 = .9375 Liters

math
505200000000000 = 505,200,000,000,000 = 505.2 * 10^12 = 5.052 * 10^14 so YES :)

Fine number but what about it?
What is the question

Chemistry
Yes, but Mols of H2SO4 in ONE LITER 3 M means 3 mols in a liter 9 M means 9 mols in a Liter

Math
sin 2 x = sin x when x = 0, 180, 360 etc

science/math
1. No If it hits at 42 from the SURFACE that is 90-42 = 48 from the normal. The reflected ray will also be 48 from the normal. 2. NO 27 + 27 = 54

Physic II
sh in cal/kg deg C = .19 *1000 = 190 heat in = mass * sh * delta T 450,000 = 100 * 190 * (50-T) 23.68 = 50-T T = 26.3 deg C

physics
1) 90 - 42 2) 27 * 2

I already answered this
Please post once. Both are very wrong.

Math
You percent is percent that will FAIL It asks for the ones that do not fail.

Math
100 - 30.2

Math
Atta go :) You are welcome.

Math
dQ/dt = 200(-.0488) e^-.0488 t

Math
A = Ai e^-kt .5 = e^-14.2 k ln .5 = -14.2 k k = .0488 so Q = 200 e^-.0488 t

Math
Now I did problems very similar to this for you earlier. You try and I will check if I am around.

Math
You sure are having quite a time with these exponential functions! y = 190 [ 1- .955 e^-(.25 t) ] If t = 9 y = 190 [ 1 - .955(.105) ] = 190 [ 1 - .1 ] = 171 cm In other words it has reached 90% of max length in 9 years now dy/dt = 190(-.955) (-.25)(.105) = 4.76 cm/year c) when...

Physics
a) Vx = 65 cos 30, Vy = 65 sin 30 b) Vx =125 cos 40, Vy = -125 sin 40 c) Vx = 5.3 sin 30 , Vy = 5.3 cos 30 of course sin 30 = 1/2 and cos 30 = sqrt3/2

Calculus
Tyler, if yu do not know how to use parentheses try to type it with lines like 1 -------- (3 t - 1) or something.

Physics
I am not going to look at this until I see some attempt by you to balance forces and moments.

physics
Pick some time over which the dB/dt takes place, say t = one second. Then dB/dt = 3.2/1 = 3.2 T/s then you can get i for that dB/dt then i * t = i * one second

World history
Netherlands ? :)

Math
2.7^3 = 19.683 15 * 19.683 = 295.245

statistics
by the way that calculator uses x - mean for z instead of (x-mean)/sigma

statistics
Here is an online normal distribution calculator: http://davidmlane.com/hyperstat/z_table.html

statistics
well, you have enough data points to use normal distribution rather than computing with binomials forever and a day. Otherwise use a program or spreadsheet to compute all the binomial coefs and powers and products mean = n p = 200 * .6 = 120 sigma^2 = 120 (.4) = 48 so sigma = ...

Math
we have already done a half life one but anyway ds/dt = k s ds/s = k dt ln s = k t + c when t = 0, ln si = c si is initial size ln s = k t + ln si ln (s/si) = k t s/si = e^kt 2 = e^k(30 min) ln 2 = 30 k k = .0231 1,000,000/50 = e^.0231 t ln (20,000) = .0231 t t = 428.6 = 429 m...

Math
.5 = e^-k T ln .5 = - k T T = -.693/-k = .693/k b) T = .693 / .0001074 = 6454 years

physics
1 C 2 less, maybe you run over the mark from the first one on the track just as the rear can explodes, and the two marks on the track are together :)

Physics
On earth I assume weight on first line = (86.4+20.8)(9.81) weight on second (lower) line = 20.8 (9.81)

physics
in the horizontal direction the ball has no acceleration once let go (no horizontal force) so now it is 9 m/s^2 down by the way, g on Mars about the same as earth ? FALSE

physic
40 g = .04 kg .04 [25 (sh ice) + heat of fusion + 100 (sh water) + heat of vaporization + 5 (sh water vapor at 1 atm) ]

algebra 2
An = A1 + (n-1)d average = (A1 + An)/2 sum = average * number of terms = n (A1 +An)/2 = (n/2) [ 2 A1 + (n-1)d ] here = (11/2) [ -24 + (10)5 ] = (11/2) (26) = 11 * 13 = 143

physics
z = 5 * 10^5 ohms i = 1/(5*`10^6) = .2 *10^-6 = 2 *10^-7

physics
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/rlcser.html

English
B. ok C. Based on his very frail appearance, a mugger might SURMISE that he would be SUSCEPTIBLE to a strong arm attack; however, that would be a great mistake.

English
My version A. I said that he was HYPOCRITICAL because he pretends to be filled with PIETY, but I know that he is a bigger sinner than I am. I wouldn't even mind that if on Sundays in church he wasn't so POMPOUS.

social studies check answers
1. disagree 2. no idea 4. agree

English
loud and intense manner.

algebra
.25 A = 48 A = 48/.25 = 48 * 4 = 192 (2/3) 192 = 2 (64) = 128

Read what you typed
Lots of dimensions missing.

Math
ds = sqrt (dx^2 + dy^2) dx = -5sin t +5 sin5t dx^2= 25sin^2 t -50sint sin5t+25sin^2 5t dy = 5 cos t -5 cos 5t dy^2= 25cos^2 t-50costcos5t +25 cos^2 5t luckily sin^2 + cos^2 = 1 dx^2+dy^2=50-50(sin t sin 5t+costcos 5t) but sin a sin b + cos a cos b = cos(a-b) = 50 - 50 cos 4 t ...

Physics
delta L/L = (T/area) / E = (215*9.81 /2*10^-5) / 8*10^10 = ( 1054 * 10^5 ) / 8*10^10 = 132 * 10-5 so delta L = (3.5)(132*10^-5) = 461 * 10^-5 = .00461 meters = .461 cm

Physics
Tension in cable = T Force up at end from cable = T sin 37 compression Force toward wall = T cos 37 max friction force = .485 T cos 37 up vertical forces on rod sum to 0 2 Fg = .485 T cos 37 + T sin 37 2 Fg = .989 T T = 2.02 Fg take moments about intersection of rod and wall c...

Physics 141
Hey. I just did that.

Physics 141
Distance axle above step edge = .33 - .125 = .205 Angle T is angle between straight down from Axle and the top edge of the step so cos T = .205/.33 T = 10.58 deg sin T = .184 Take moments about the top edge of the step. F * .205 clockwise (my step is on the right) m g * .33 si...

Physics 141
T = 1/4 so f = 4

Physics 141
after one period T, (8 pi T) = 2 pi so T = 1/4 so f = 1/T = 4

math
first .2*9.45 = 1.89 remaining length = 9.45 - 1.89 = 7.56 so piece 2 + (piece 2 - .12) = 7.56 2 * piece 2 = 7.68 piece 2 = 3.84

Civil War
It did sort of.

strange question but
You can easily figure out the velocity of each. It has nothing to do with the mass. (1/2) m v^2 = m g h note m cancels v = sqrt (2gh) so for example for 2.5 meters v = sqrt (2* 9.81*2.5) = 7 meters/second -------------------------- The only force here is gravity itself F = m ...

physics
(1/2) L i^2 = (1/2) C V^2 i^2 = (C/L) V^2 i^2 = (3.1*10^-6 / 5.6*10^-3) (961) i^2 = 532 * 10^-3 = 53.2 * 10^-4 i = 7.3 * 10^-2 = .073 amps

physics
period = 1/frequency = (1/7.01)*10^-18 wavelength = 3*10^8 (1/7.01)*10^-18 = .428 * 19^-10 = 4.28 * 10^-11 meters

Statistics
I also agree

Pre calculus
if it is x^3 + 2 x^2 - 15 x + 20 = 0 then: http://www.mathportal.org/calculators/polynomials-solvers/polynomial-roots-calculator.php gives x = -5.44 x = 1.72 +/- .853 i

physics. PLEASE HELP
If it is 50 meters high, the pressure is the weight of a one meter square column 50 meters high. Water density is about 1000 Kilograms/ cubic meter So the mass of this column is 1000 Kg/m^3 * 50 m * g or 1000 * 50 * 9.81 = 490,500 Newtons that weight is spread out over the one...

Physics
work done = increase in kinetic energy (here we have a decrease so the work is negative. The force is opposite to the direction of motion) work = (1/2)(4.5*10^4)(5000^2 - 7000^2) work = force *distance moved in direction of force so Force = work/(1.4*10^6)

Physical science
k Q1 Q2 / d^2 1) if d2 = 3 d 1 then 1/d^2^2 = 1/(3d1)^2 = (1/9) 1/d1^2 2) k Q1 (2 Q2)/d^2 = twice original

speech-english
I am tempted to just say model right off the bat but it depends on the audience and the setting. If it is a big crowd in an auditorium a model might not be very easy to look at from all angles and see inside it. Then photographs or a flip chart might be better. If the opportun...

Physics
original east momentum = 2115*10.61 final east momentum = (2115+3169)*5.03cos32.4 22440 = 5284 * 4.25 v = 22440 v v =1 m/s

physics
not of the mass itself, but about some other point. For example for a point mass hanging from a nail on a string it is m L^2 about the attachment point at the ceiling where L is the length of the string.

Math (how do you find the volume of a cone)
for any object with a point at the top and straight sides use (1/3) height * area of base

Physics
r = 1.5 * 10^-3 m pi r^2 = pi (2.25) * 10^-6 m^2 F/A = P = 2*10^4 /[pi (2.25) *10^-6) ] = .283 *10^10 = 2.83 * 10*9 Pascals

Physics Help
You have: velocity v = dx/dt = -A*ω*sin(ωt) so what is -A omega ? A = 3.5 omega = 2 pi f = .848 so - A omega = -2.968 or -2.97

Geometry
http://www.jiskha.com/display.cgi?id=1396301143

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