Wednesday
July 23, 2014

Posts by Damon


Total # Posts: 17,501

Math
combinations of 7 taken 4 at a time C(7,4) = 7! /[ 4!(3!)] = 7*6*5/(3*2) = 35

Physics
T = tension mass 1 = 30/g mass 2 = 20/g for mass 1 m a = m g - T (30/g)a = (30/g) g - T for mass 2 (20/g) a = T - (20/g)g add the two equations (50/g) a = (10/g) g so a = g/5 or about 9.81/5 = 1.96 m/s^2 that is Part B go back and get T for part A then for part C chain tension...

Calculus
2 x^2 + 4 x h = 600 h = (600 -2 x^2 )/4x or h = (300 - x^2)/2x v = x^2 h v = (1/2)( x)(300 -x^2) v = (1/2)(300 x - x^3) dv/dx = (1/2) (300 - 3 x^2) = 0 for max or min so x = 10 then x^2 = 100 h = 10 v x^2h = 1000

science
For electricity: coal, wood, gas, running steam generator , or diesel generator or solar, geothermal, water wheel, wind turbine choice depends on where you are, do you have water power available? geothermal handy? strong winds? Southern exposure to sun?

rounding
Yes

Algebra
4 sqrt 10 - 1 sqrt 10 = 3 sqrt 10

Algebra
well, it is hard for me to graph here so eliminate y by subtracting the second equation from the first x^2 + 5 x -50 = 0 (x-5)(x+10) = 0 so x = 5 or x = -10 if x = 5, then y = -10 if x = -10 then y = 35

Algebra
if -3m = 0, then the whole thing is 0 so if m = 0, the whole thing is 0 if (2m-5) is 0, the whole thing is 0 so if m = 5/2, the whole thing is 0 so the solutions are m = 0 and m = 5/2

when the energy of a sound wave is transferred to
Hey, what do you think the answers are and why ? You can figure it out even if you do not know much physics.

math HELP!!!!!!
You are welcome :)

math HELP!!!!!!
16/40 = x/700 2/5 = x/700 x = 1400/5 = 280

physics
m g h

math HELP!!!!!!
Yes, C

math HELP!!!!!!
no review your text about valid sampling and bias

MATH!!!
V = 156 + 4.5 (t - 12)

Algebra
16 t^2 -20 t - 6 = - h in obsolete English units when does h = 0? t = [ 20 +/- sqrt (400 + 384) ] /32 t = [ 20 +/- 28 ] /32 t = 48/32 = 1.5 seconds (ignore the negative t) for vertex complete the square assuming no calculus may be used 16 t^2 -20 t = - h + 6 t^2 - (5/4) t = -h...

Math
p(f) = 3/20 p(first) = 3/20 = .15 p(second) = 2/19 = .105 p first and second = .15 * .105 = .0158 first fail, second pass = 3/20 * 18/19 first pass second fail = 17/20 * 3/19

Physics
.050 Vo = 1.050 v so v = .0476 Vo initial Ke = (1/2)(.05)Vo^2 final Ke = (1/2)(1.05)v^2 100 (.05 Vo^2 - 1.05 v^2) /.05 Vo^2 100 (.05 Vo^2 - .00238 Vo^2)/.05 Vo^2 = 95.2 % of initial energy is lost

Physics
(1/2)(1200)(900) = 540,000 joules m g h = 1200 * 9.81 * h = 540,000 h = 45.9 meters

College Algebra
x (x-9) =0 x = 0 and x = 9 are correct ps I bet they meant: x^2 - 9 = 0 (x-3)(x+3) = 0 x = 3 or x = -3

Math
arithmetic series see http://www.mathwords.com/a/arithmetic_series.htm here a1 = 30 and d = 4 and n = 10

What is the coefficient of x?
-5

Physics
R = 10 + 8 + 27 i = 9/R for each Vn = i * Rn the sum of Vn better equal 9

Math
a + c = 390 a = 2.25 c so 2.25 c + 1 c = 390, solve for c then for a Revenue = 8 a + 3 c

Math
You are welcome.

Math
tan angle = 34/12

science
When you post a question again and again and no one replies, perhaps there is something missing in the question that renders it incomprehensible. We have no idea where or what you are talking about, on a beach or in a bottle or what else is behind your question.

algebra2/ Trigonometry
24+22+14+12 = 72 marbles yellow = 14/72 = .1944.... or about 19.4 % do the others the same way

Geometry
You are welcome.

Geometry
Volumes scale as the CUBES of corresponding lengths of similar figures (25/35)^3 = (5/7)^3 = 125/343

typo
I have no idea what you mean there are about 6*10^23 anythings per mole just like there are 12 anythings per dozen

trigonometry ans.
You are welcome.

trigonometry ans.
right, you asked for nearest foot

trigonometry ans.
tan 53 = height/distance yes, 66 to nearest foot The right angle is at the foot of the tree. ALWAYS draw a picture tan 53 = opposite (tree) / adjacent(along ground the hypotenuse is along your line of sight, not used here

physics
momentum after momentum before sum of m after v after = sum of m before v before .16 (27.5) + (68) v = 68.16 (2.55) solve for v second skater: (60.5+.16) v = .16(27.5) solve for second skater v

Geometry
ok, always sketch a graph

Geometry
It gets smaller.

help
You are welcome.

help
tan 12 = 40/d d = 40/tan 12 = 188 meters ! If that diver is wearing a hard hat, he is going to be a wreck himself by the time he gets there and it will take so long that he will need to make decompression stops upon ascent to avoid getting the bends. Move the stupid ship !

Geometry
You are welcome.

Geometry
https://www.khanacademy.org/math/geometry/similarity/triangle_similarlity/v/similarity-postulates

Geometry
http://www.regentsprep.org/Regents/math/geometry/GP11/LsimilarProof.htm

Geometry
ratio of areas of similar figures is ratio of corresponding lengths squared 20/16 = 5/4 so 25/16

algeba/can you please ck my answer
1598 * 1.05 = 1677.90 total cost with tax 1677.90 * .14 * 3 = 704.72 total interest so total amount to be paid = 2382.62 divide by 36 months = 66.18 per month Note this "add on rate" is a rip off. As you pay the principal back, the amount you owe should decrease. If ...

Algebra 1
Nasty !!! at 2:30 m

Algebra 1
Oh delete the x = 5, denominator of original is 0 Not in domain

Algebra 1
{ (6x-14) + (x^2-5x) ] /[2(x-5) ] =16/[2(x-5)] x^2 + x - 14 = 16 x^2 + x - 30 = 0 (x-5)(x+6) = 0 x = 5 or -6

math
7 n = 400 - 190

statisticsWere did i go wrong thank you
I am happy to help. You are welcome :)

statisticsWere did i go wrong thank you
mean = 97 correct difference and square of difference -14 196 -1 1 3 9 3 9 9 81 sum of squares = 296 variance = 296/5 = 59.2 square root of variance = standard deviation = 7.69

whoops, order wrong
then divide by n then take the square root

statisticsWere did i go wrong thank you
http://www.mathsisfun.com/data/standard-deviation-calculator.html

statisticsWere did i go wrong thank you
then take the square root, then divide by n

statisticsWere did i go wrong thank you
The differences SQUARED

Physics
u = 1540 cos 52 = 948 the whole time Vi = 1540 sin 52 = 1214 at start v = Vi - 9.8 t 0 = 1214 - 9.8 t t = 124 seconds to top so 2 t = 248 seconds in the air (part B) range = u * 2t = 234,871 meters or 235 km

Statistics/I am confused
difference from mean = 115-105 = 10 below mean variance = 25 so standard deviation = 5 so z = -10/5 = -2 it is two standard deviations below mean for z = 2 look up in normal table http://davidmlane.com/hyperstat/z_table.html probability = .0228

algebra
|+1 +0 | |-2 +3 +8 | |+0 -1 | |-3 +5 -1 | = | -2 +3 +8 | | +3 -5 +1 | so (-2,3), (3,-5), (8,1)

geography
Just some suggestions 1. Location maybe in Southern California on the west coast of USA. 2. Place What defines this place? Hollywood? Freeways? 3. Human interaction with environment You have to mention smog and the use of cars and air conditioning. You have to point out that t...

math
(y+6)^2 + (-6)^2 = 100 y^2 + 12 y + 36 + 36 = 100 y^2 + 12 y - 28 = 0 (y-2)(y+14) = 0 y = 2 or -14 y = 2 is on your list

Math
Note the tangent is perpendicular to the radius where it hits the circle.

Math
21/2 is rational but not integer and it is more than 5 and more than 2 so a square would solve the problem. put points at (21/2, 21/2) in quadrant 1 then its image (-21/2, 21/2) in quadrant 2 then (-21/2, -21/2) in quadrant 3 and (21/2,-21/2) in quadrant 4.

Statistic
5. 115 - 100 = 15 z score means how many standard deviations away from mean so 15/10 = 1.5 A+ :)

Statistic
http://easycalculation.com/statistics/standard-deviation.php

Multiply write the result in scientific notation.
(9*10^4)(8*10^6) = 72^10^10 = 7.2*10^11

physics
10 * 44 = 440 meters

geometry
volume = (1/2) (4/3) pi r^3 = (2/3)pi r^3 so 486 pi = (2/3) pi r^3 so r^3 = (3/2)(486) = 729 area of half of hemisphere = (1/2) 4 pi r^2 = 2 pi (729)^(2/3) = 162 pi

physics
a = F/m a = (2.36 cos 44.8 ) /.22

algebra
Evaluate 3p/q when p=2 and q=6. Answer:1 YES Use < > or = for __ to write a true sentence: 0.001 __ 0.0010 Answer:< Question 3 _______________ = ___________________ Evaluate -3/8 - 5/8. Answer:7 Question 4 ____________________ -8/8 = 1 __________________ Evaluate: 84 ...

engineering mechanics
Just look at the solved problems linked below. This problem may be the most common in all of algebra and beginning physics :) Remember and hour is 3600 seconds.

math
Equations have = signs

trig
(1 + tan^2A)(1 -sin^2A) but (1 - sin^2 A) = cos^2 A and (cos^2A/cos^2A + sin^2A/cos^2 A) = 1/cos^2 A so we have (1/cos^2 A)(cos^2 A) which is 1

math
tan theta = 9/175

Math
Nor do I. Have you mixed up two problems?

math
11 + 5 = 16

Science
Mass does not depend on gravitational constant anywhere. 5 kg is 5 kg b) m g = 5*9.81 N

ENGLISH
Pretty Calf says exactly why.

math
Find LCD 40 = 2*2*2*5 25 = 5*5 10 = 2*5 so 2*2*2*5*5 = 200 so 15/200 , 32/200 and 20/200 3/40 1/10 4/25 B

precal help asap
There are in fact an infinite number of solutions I would try each of the choices I have my calculator set on degrees so 2pi = 360 tan^2 (360/3 ) = 3 Yes that works tan 180 does not work tan -60 does not work tan 300 = nope so only A

algebra/please help I have been wrong twice
You are welcome.

algebra/please help I have been wrong twice
p(oil) = 1/40 p(gas) = 1/20 p(oil and gas) = 1/800 so (1/40)(395,000) = 9875 (1/20)(125,000) = 6250 (1/800)(520000) = 650 So I get 16,775 income - 25,000 expense = -8225 They expect to lose money I think.

PRECAL MULTIPLE CHOICE
sin A/a = sin B/b sin B = (b/a) sin A = 1.036 no solution (sin may not be greater than 1)

math
f' = -12 x^2 + 16 x + a f" = -24 x + 16 sheds water when when f" is negative holds waster when f" is positive f" is 0 when x = 2/3 sheds water when x < 2/3 holds water when X>2/3 so B

math
f(4) = 64 f(1) = 1 63/3 = 21 = average slope in interval f' = 3 x^2 = 21 x = +/- sqrt 7 in interval x = sqrt 7 = c so A

Physics
g is about 32 ft/s^2 in these obsolete units 61.8 miles/hr * 5280 ft/mi * 1 hr/3600seconds = 90.6 ft/s 7 * 32 = 224 ft/s^2 a = change in v/change in tim 224 = 90.6/t t = .4 seconds

Science
+2e

Science
By the way, remember transportation losses and expenditures including expense and losses of electrical cables particularly under sea.

Science
Actually I did not intend to write a PhD thesis before lunch. Post your attempt first please. Use the sources you have learned about (coal, oil, natural gas (fracked or otherwise) , nuc, hydro, wind, waves, solar panels etc )

physics
away of course in general for non-relativistic Doppler effect f heard = f emmitted (c+vr)/(c+vs) c = v of wave vr = v receiver (plus if toward source) vs = v source, (plus if source moving away from receiver) use your c of sound 78 = 80 (c+0)/(c+vs)

calculus
Horizontal speed constant forever = 80 cos 45 = u = 56.6 ft/s Initial vertical speed Vi = 80 sin 45 = 56.6 ft/s Now you did not give me the quadratic so I will have to solve it with physics v = Vi - g t where g = about 32 ft/s^2 in these obsolete units then h = Hi + Vi t - 16 ...

English
I think it could mean one of two things: 1. Instead of arguing about who would pay how much, I "simply" picked the bill up. 2. I "just" picked the bill up a minute ago.

Math
2/50 - 75/50 = -73/50

technology
work in = work out 10 * 100 = F * 20 F = 50 N

Physics
volume of man = 75 liters so density of man = 80 kg/75 L = 1.067 kg/L x(fat density ) + (1-x)(bone density) = 1.067 .9 x + 1.1 (1-x) = 1.067 1.1 - 1.067 = (1.1-.9)x x = .167 or 17%

Algebra 1
sorry, read reply wrong. You have it fine

Algebra 1
number or blacks = b number of whites = b+10 total - b +b+10 = 2 b+10 black first b/(2b+10) now we have b-1 blacks we have b+10 whites still total = 2b+9 b/(2b+10) * (b+10)/(2b+9) note - not 2b+10 in numerator

trig
rise = .1 run tan theta = .1 theta = 5 deg

algebra
36 possible outcomes if order matters If it is the sum that matters you have to figure a different probability for every sum for example there are 4 ways of getting a sum of 5 1+4 or 4+1 2+3 or 3+2 to get a sum of 6 though, there are 5 ways 1+5 or 5+1 2+4 or 4+2 3+3 On the fir...

algebra
I suspect they mean including 1 and 100 and not 2 through 99 so 100 numbers total so 5, 10, 15 ...... 100 are multiples How many? 10 * 2 = 20 20/100 = 1/5 so 1 - 1/5 = 4/5

Trig
current north speed = 3.2 sin 38=1.97 N current west speed = 3.2 cos 38 = 2.52 W Total North speed = 8.5+1.97 = 10.47 Total west speed = 2.52 tan theta = 2.52/10.47 theta = 13.53 degrees west of north or 47.47 degrees north of west Is the direction you are GOING (you are still...

trig
cos 35 = h/15

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