# Posts by Scott

Total # Posts: 2,129

**stats**

the dice are independent chance (probability) of a 5 is ... 1/6

**physics help please**

the difference in the path length between the direct and reflected sound should be an odd half wavelength to facilitate cancellation ... 1/2, 3/2, 5/2... the speed of sound is 340 m/s so the wavelength is 340/440 m the diagram is an isosceles triangle with an altitude of 2 m...

**math need help now**

as bob says "all REGULAR n-gons are similar" C for sure (they're regular) D doesn't say "regular"

**math**

you're looking for an area of 80 try C

**Physics**

vol = m / d = 20 kg / 20Mg/m^3 = 1 L the stone displaces 1 L of water with a mass of 1 kg the stone's weight is ... 19 * g

**math**

pay = [$.01 * 2^(day)] - $.01

**Physics **

did your G have the right units? you are correct that either equation should work Fg = Fc ... in orbit ... recalculate, and watch your units

**Science**

blood comes from the body ... goes to the lungs ... comes back from the lungs ... goes back out to the body the blood drops off carbon dioxide and water in the lungs and picks up oxygen, which is carried out to the body look up the exact flow through the heart chambers ...

**physics**

the surface is frictionless, so T is providing acceleration to the boxes the accelerating force is transferred to the small box by friction between the boxes at some point (as T increases), the frictional force will not be enough to provide the necessary acceleration and the ...

**chemistry**

.100 L * .10 M/L = .010 M .010 M / 4.0 M/L = ?

**chemistry**

each mole of butane yields 5 moles of water a mole of gas at stp is 22.4 L 10/22.4 * 5

**probability**

this is a binomial result ... win or not win P(w) = .15 , P(n) = .85 (n + w)^10 ... you want the 3rd term 10C2 * .85^8 * .15^2

**Physics**

the acceleration is ... g sin(38.0º) d = 1/2 a t^2 ... t = ?(2d / a)

**Chem**

you need to combine the given reactions ... some partial and/or reversed ... to get the desired reaction 2CO2 + H2O --> C2H2 + 5/2 02 ?H = 1300 kJ 2C + 2O2 --> 2CO2 ?H = -788 kJ H2 + 1/2 O2 --> H20 ?H = -286 kJ add the 3 reactions, along with the ?H's ... cancel ...

**Math**

1 cm on the original is 20 cm on the transfer

**chemistry**

not enough nitrogen a mole of nitrogen is needed for every 3 moles of hydrogen

**math**

tan(?) = 250/170

**Math**

v = 24 (1 + .06)^385

**physics**

2 * vertical velocity / g 16.7 * ?2 / 9.81

**Algebra**

(a) m = 500 (1 + .015)^t (b) 800 = 500 (1 + .015)^t ... 1.6 = 1.015^t ... log(1.6) = t log(1.015) ... [log(1.6)] / [log(1.015)] = t

**Algebra - PLEASE HELP!**

231 = -17.5x2^ - 138.5x - 27 462 = -37 x^2 - 277 x - 54 0 = -37 x^2 - 277 x - 516 use quadratic formula to find x

**probability**

there are 9 pairs of cards that differ by one ... 1-2, 2-3, 3-4, etc. there are 10C2 possible pairs ... 45 so the probability of a pair differing by one is 9/45 or .2 ... by more than one is (1 - .2) = .8 3 cards contain 3 pairs .8^3 = .512

**physics**

m g h = 1/2 m v^2 ... v = ?(2 g h)

**physics**

it's a fraction of a mole ... 9.1E5 / 6.02E23 multiply the fraction by the molar mass

**physics**

60 sec in a min 2.54 cm in an inch 9.843E4 ft/min * (1 min / 60 s) * ... (12 in / 1 ft) * (.0254 m / 1 in)

**physics**

f = m a = 2E3 kg * ... [(20 m/s - 5 m/s) / 4 s] answer is in Newtons

**Algebra2**

an = 13n - 8

**Physics**

convert mph to m/s convert cg(?) to kg K.E. = 1/2 m v^2

**physical science**

Joules of energy required ... 202 * (95.6 - 22.0) * 4.18 divide by heater wattage ... 1 watt = 1 Joule per second divide by 60 ... sec to min

**Physics**

friction

**science**

free fall...starting from rest d = 1/2 g t^2 ... plug in the times, and find the difference in the distances the 1st body will always be going faster than the 2nd, so the distance between them is always increasing

**Math**

the edge length is the cube root of the volume 8 in this case

**Math**

not enough information

**Maths**

the distance between the centers of the two outer circles is 4 they are in the diagonal corners, and their centers are ?2 from the corners so the diagonal of the square is ... 4 + 2?2 dividing by ?2 to find side length ... 2 + 2?2 squaring ... 4 + 4?2 + 4?2 + 8 = 12 + 8?2

**Math**

order counts 6P3

**physics**

the work ... 7.6N * 8.6m ... is equal to the block's KE 1/2 * 0.50 * v^2 = 7.6 * 8.6

**Math 125**

sometimes just using numbers will clarify for 2000 people ... 10 have the virus ... 8 will test pos ... 2 will not ... 1990 do not have the virus ... 199 will test pos a) 207 people test pos ... 8 of them have it ... 8/207 = .0386 b) 1793 people test neg ... 2 of them have it...

**physics**

20^2 = 10^2 + v^2 sin(?) = 10/20 ... north of west

**College Chem**

heat gained by water equals heat lost by metal 50.0 * (t - 20.0) * 4.182 = ... 1000 * (100.0 - t) * 0.50

**Physics**

you know the size of the disk, and the material (aluminum) calculate the volume and look up the density

**Physics 202-help**

15/3 = 5 ... storm distance in km 15s * 343m/s = theoretical distance the time for the light to travel is below the sig fig of the other measurements ... it can be considered instantaneous

**backwards math**

(6 + 6 - 5) * 4

**Algebra**

u = t + 7 10u + t = 3(10t + u + t + u) ... = 33t + 6u 4u = 32t solve the system by substitution or elimination

**math**

x (154) + (40 - x)(170) = 40 (160)

**Math**

v / 125 = [v / (125 + 25)] + 4/3

**Physics**

1) the sound goes over and back ... 2 w =5.7 * 343 2)velocity = frequency * wavelength ... v = (2.22 / 7.59) * .168 m

**Physics**

3 s measures the km to the lightning 5 s measures the miles

**Algebra**

(k - 10)(k - 2) (2x + 7)(3x - 2)

**maths**

45 * (1 + .10)^20

**too-hard probability sir damon/reiny/steve help**

"you can lead a horse to water...but you can't make him drink"

**too-hard probability sir damon/reiny/steve help**

this is binomial...with a twist P(b) = .4 , P(w) = .6 (b + w)^4 b^4 + 4 b^3 w + 6 b^2 w^2 + 4 b w^3 + w^4 P(w ? 0) = 1 - P(b = 4) = 1 - .4^4 P(b = 2) = 6 * .4^2 * .6^2 divide to find the conditional

**Physics**

the given data is unrealistic please check it

**physics**

the ball is uniformly accelerated by gravitational force the velocity is zero at the peak 1.5 s before the peak, the velocity is ... 1.5 * g upward 1.5 s after the peak, the velocity is ... 1.5 * g downward

**PreCalc**

18 t + 5 t - 5 = 12

**Algebra 2**

x y = k

**Algebra 2**

the job takes 96 people-hours so for 3 people... 96/3 hr

**Exponential Equation**

4E12 = 24 * e^388r ln(1.7E11) / 388 = r

**Math**

3 1/2 is 28 eighths

**Math**

the scale is logarithmic 10^(8.3 - 6.2)

**Geometry**

the four given sides sum to 24 so the 5th side is 6 ... 30 - 24

**Algebra**

x + 2y = 150 x + 4y = 260 solve the system

**physics**

the net force is ... f = m a ... f = 111.5 * 2.7 net force is tension minus gravity t = 111.5 (9.8 + 2.7)

**Chemistry**

2 KClO3 ---> 2 KCl + 3 O2 moles O2 = 3/2 * moles KCl moles KCl = mass KCl / molar mass KCl mass O2 = moles O2 * molar mass O2

**chemistry**

find grams of C in CO2 and grams of H in H2O convert the grams to moles (divide by the molar masses) the mole ratio will give you the empirical formula

**college algebra**

h = 1/2 g t^2 + v t + Ho 44 = -4.9 t^2 + 20 t + 37 solve the quadratic for t

**Math! Please help!**

15 ? -k/4 - 9 24 ? -k/4 96 ? -k ... -96 ? k

**Chemistry**

381 pm is the edge length of the cubic unit cell the atomic radius is the edge length multiplied by ... ?2 / 4

**Math**

2 is 12/6 so you need the lowest common multiple of 12 and 5 ... 60 60/6 = 10 ... five 2 lb bags

**math**

looking at the cross section, this is a circle in an equilateral triangle

**math**

looks good

**math**

plug the points into the general equation and solve the system P...1 = a - b + c Q...1 = a + b + c R...6 = 25a + 5c + c

**math**

P and Q are the same point need 3 DIFFERENT points

**Chemistry**

22.4 L/mole ... gas at stp octane is 114 g/mole 2 C8H18(g) + 25 O2(g) ---> 16 CO2 (g) + 18 H2O(l) (39.0 / 114) * 12.5 * 22.4 L

**physics**

work = force * distance f = 5497 / 22.1 a = f / m = 5497 / (22.1 * 3090) d = 1/2 a t^2 ... t = ?(2d / a) v = a t

**Algebra**

3a + 9c = 183 ... 6a + 18c = 366 6a + 13c = 276 subtract equations to eliminate a solve for c, then substitute back to find a

**Algebra**

(r + 3) / 79 = r / 15 15 r + 45 = 79 r

**sciance**

depends on the car

**Physics**

yes the up-thrust (bouyancy) is a function of the VOLUME of liquid displaced

**grade7 math**

the rectangle with the least perimeter is a square

**Chemistry**

you aren't given the atomic mass not enough data for a solution

**Chemistry**

the volume of hexane is ... 338 g / .66 g/mL the height of the liquid is ... (hexane vol) / (? *2.91^2)

**physics**

energy = 1/2 m v^2 energy / time = power

**Algebra 2**

a^b = 3^3 3^(1/2)^x = a^(1/6) 3^3^x = a 3^3 = a^(1/x) x = 1/b

**math**

the slope is the same everywhere on the line slope = (-5 - 7) / (-5 - 4)

**math**

the distance is constant, so speed and time are inversely proportional t / 28 = 65 / 78

**Math**

c (100% - 56%) = 202.92

**Math**

m = [(91 - 44.39) / 44.39] * 100%

**physics**

how thick is the ice?

**math**

adding equations to eliminate e ... 3d = 12 solve for d, then substitute to find e

**Math**

3.36E6 poeple / 3 per household = ... 1.12E6 households 2 bags per month = 24 bags per year ... 10 lbs per bag 1.12E6 * 24 * 10 = ?

**Math**

a square m is 10000 square cm

**chem**

it will appear that there are more moles of solute than are actually present you will be dividing the mass of added solute by too large a number ... this will result in the molar mass being too low

**geometry**

the two angles sum to 180º x + (4x + 50) = 180

**Chemistry**

that's what you start with ... some of it is precipitated out also, the volume of the solution is more than doubled (remaining PbCl2) / solution volume

**Science ms sue please help**

the question specifies "chemical property"

**Science ms sue please help**

if there is no reaction...what are you observing?

**algebra**

c + r = 4.5 14c + 8r = 51 solve by substitution or elimination

**Mathematics**

x = -3 (y + 1) x^2 = 9 (y^2 + 2y + 1) substitute and solve for y there will probably be two solutions ... the intersection(s) of a circle and a line

**Algerbra**

the vertex is on the axis of symmetry ... x = -b / 2a f(x)=x^2+2x-3 ... x = -2 / 2*1 = -1 f(x)=x^2-3x+1 ... x = - -3 / 2*1 = 3/2 plug the x's into their functions to find the y's for the vertex coordinates

**math**

sin(0) = 0 ... sin(90) = 1 so ... sin(50) > sin(40) cos(0) = 1 ... cos(90) = 0