Sunday

May 24, 2015

May 24, 2015

Total # Posts: 21,038

**Math! Please check!**

Got it ?
*October 7, 2014*

**Math! Please check!**

Yes and yes To remember forever: 1. Hypothesis: If cow , then mammal 2. converse: If mammal,then cow (maybe) 3. inverse: If not cow, then not mammal (maybe) 4. contrapositive: If not mammal, then not cow (true) Make Venn diagrams for the situation :)
*October 7, 2014*

**Math**

http://davidmlane.com/hyperstat/z_table.html
*October 7, 2014*

**math**

(5/4) *120 = 5 * 30 = 150 pennies which is $1.50
*October 7, 2014*

**math(fractions)**

but 90/20 is 9/2 which is 4 1/2 which is 4.5
*October 7, 2014*

**Algebra**

It is going to be ten times as big.
*October 7, 2014*

**Algebra**

how many 125s in 8450 ? 8450 ----- = 67.6 so 67 full rows 125
*October 7, 2014*

**Algebra**

well, we sure seem to be into division :) 384,400 -------- = 110.587 so 111 3476 because .587 is more than half way from 110 to 111
*October 7, 2014*

**Math! Please check!**

I agree with all of your choices.
*October 7, 2014*

**physics**

v = Vi + a t 152 = 0 + 1.35 * 10^4 t but 1.35 * 10^4 = 135 * 10^2 t = (152/135) * 10^-2 = 1.13 * 10^-2 = .0113 seconds
*October 7, 2014*

**What pulley system**

I have no idea what your block and tackle looks like so can not calculate the mechanical advantage. Divide 1000 by the number of parts of the line pulling up on the piano.
*October 7, 2014*

**PHY1015S**

Two of them :)
*October 7, 2014*

**Math**

if you do not know calculus area of surface = pi d^2/4 area of surface * change in height/min = volume/minute pi d^2/4 * .24 m/min = pump rate - leak rate
*October 5, 2014*

**Math**

0.16 c = 4 so c = 4/0.16 = 25 then yes, subtract 4 and get 21
*October 5, 2014*

**Confusing increase in percent**

That is always confusing and the thing to remember is that doubling is 100% increase.
*October 5, 2014*

**Math**

If the result is 400% of the original 100%, then the increase is 300% +100% = doubled +200% = tripled +300% = quadrupled
*October 5, 2014*

**Physics gr. 12**

You went about this correctly. I did not check the arithmetic.
*October 5, 2014*

**Math**

+++++++ 2 x___+ 1_______ 5x-6 / 10 x^2 - 7 x - 6 ++++++ 10 x^2 -12 x +++++++++++++++ 5 x - 6 +++++++++++++++ 5 x - 6 Remainder = 0
*October 5, 2014*

**math**

at t = 0 xA = -20 , dxA/dt = -24 yA = 0, dyA/dt = 0 xB = 0, dxB/dt=0 yB = 0 , dyB/dt = 25 Dx = differnce in x location = 20 + 24 t Dy = difference in y location = 25 t distance = (Dx^2+Dy^2)^.5 distance = [ 400+480t+576t^2+ 625t^2 ]^.5 = [1201 t^2 + 480 t + 400 ]^.5 d distance...
*October 5, 2014*

**solve long divison polynomials**

http://www.jiskha.com/display.cgi?id=1412542641
*October 5, 2014*

**probability;math**

By the way, they were trying to trick you. If the Jack were NOT replaced, there would only be 51 cards when you went to pick the 8. Then it WOULD HAVE BEEN 4/52 * 4/51
*October 5, 2014*

**probability;math**

as long as it is replaced, the events are independent 4/52 * 4/52
*October 5, 2014*

**Physics**

v = Vi + a t Vend = 24 + 35 (1.9) angle at 1.9 s = 1.9(Vi+Vend)/2 total angle = 436 + angle at 1.9 s time at Vend = 1.9 + 436/Vend
*October 5, 2014*

**Math Growth Rate w/ inflation**

1.5 = (1+r)^3 log 1.5 = 3 log (1+r) 1 + r = 1.1447 r = .145 so 14.5 percent 1.08 = 1.1447^n find n continuous 1.5 = e^3k ln .5 = 3 k
*October 3, 2014*

**Physics**

4.92/360 = 500/c c = 36,585 km approximate check a degree on a great circle (around any circumference) of earth is 60 nautical miles :) (1.852 kilometers / naut mile) 360 * 1.852 * 60 = 40,000 close enough
*October 3, 2014*

**Math**

3.647 - 3.003 = 0.644 = 0.6
*October 3, 2014*

**Math (Confused, no idea where to begin)**

if t = 5 2 e^-(.16*5)=2 e^-.8 = 2/e^.8 = .899 = .90 volts 1 = 2 e^-(.16t) ln .5 = -.16 t t = 4.33 seconds at 0 sec V = 2 at 5 seconds V = .90 V = Vi (r)^t .9 = 2 r^5 .45 = r^5 log .45 = 5 log r r = .852 so every second multiply by .85 so decreases by 15% every second
*October 3, 2014*

**error**

parallel to y = 5 x - 6 so slope = 5 so dp/dx = 5 at x = 4 dp/dx = slope(x) = (x-1)(1) + (x+k) (1) = x - 1 + x + k = 2x+k-1 at x = 4, dp/dx = 7+k so 7+k = 5 k =-2
*October 3, 2014*

**CALC AB**

parallel to y = 5 x - 6 so slope = 5 so dp/dx = 5 at x = 4 dp/dx = slope(x) = (x-1)(1) + (x+k) (1) = x - 1 + 1 + k = x+k at x = 4, dp/dx = 4+k so 4+k = 5 k = 1
*October 3, 2014*

**Math**

cos theta = .2
*October 3, 2014*

**Calculous Pre**

I guess by growth rate you mean with yearly compounding and continuous means e^kt if yearly for three years 15 = 11 (1+r)^3 1.3636 = (1+r)^3 log 1.3636 = 3 log (1+r) 1+r = 1.1089 so r = .109 = 10.9 percent now if continuous 1.3636 = e^3k ln 1.3636 = 3 k k = .103 or 10.3 ...
*October 3, 2014*

**Math Calculous Hey**

Hey, I just did two of these, please use one name and do not ask me to do a whole bunch of virtually identical problems.
*October 3, 2014*

**Pre-Calc**

a b^t = 2 e^(8t) ln a + t ln b = ln 2 + 8 t a = 2 and ln b = 8 so b = e^8 = 2980 so I agree
*October 3, 2014*

**physics**

Fn = 62.6 Fw = 45.9 |F| = sqrt (62.6^2+45.9^2) = 77.6 angle north of west = tan^-1 (62.6/45.9) = 53.8 degrees so to cancel that 77.6 at 53.8 south of east
*October 3, 2014*

**PHYSICS**

work = force * distance in direction of force 2.5*10^-4 = .36 x x = 6.9*10^-4 meters
*October 3, 2014*

**Physics**

I will assume he just stops the descent of the ball change of ball velocity = 29 m/s a = change of velocity/time = 29/(16*10^-3) = 1.81 * 10^3 m/s^2
*October 3, 2014*

**Physics**

F = G Mm/r^2 F = m a = m v^2/r so G M m/r^2 = m v^2/r v^2 = G M/r G M same for both va^2 ra = vb^2 rb but va = 82 vb 6724 vb^2 ra = vb^2 rb so rb = 6724 ra circumference = 2 pi r period = circumference / v = 2 pi r/v period a = 2 pi ra/82 vb period b = 2 pi 6725 ra/vb 1/82 / ...
*October 3, 2014*

**CALCULOUS**

1.043^n = 2 n log 1.043 = log 2 n = log 2/log 1.043 = 16.5 years
*October 3, 2014*

**Science**

http://www.jiskha.com/display.cgi?id=1412288943
*October 2, 2014*

**Very important**

Go back and read my reply about the bottles moving at constant velocity !!!!
*October 2, 2014*

**Science**

a = 2 (1.5)/3.6^2
*October 2, 2014*

**sign error**

-h/h or -1
*October 2, 2014*

**Math**

f(2+h) = |2+h-5|-7 = |h-3| -7 as h---> 0 this is 3-h-7 = -h -4 f(2) = |-3| -7 = 3-7 = -4 so [ -h - 4 + 4 ] /h = h/h = 1
*October 2, 2014*

**What collision, where?**

I do not read minds.
*October 2, 2014*

**Physics**

I just showed you how to do the one with the train and the car.
*October 2, 2014*

**Physics**

car: v = 36 + 4 t x = 35 + 36 t + 2 t^2 train v = 22 x = 22 t the time t and the position x are the same at passing 22 t = 35 + 36 t + 2 t^2 solve quadratic for t go back and find v = 36+4t
*October 2, 2014*

**physics**

F sin 30 = 1.2 sin 30 = 1/2 F = 1.2/(1/2) = 2.4 N
*October 2, 2014*

**Science**

NO No NOOOO !!!!!! constant velocity is NO FORCE very, very important Force = mass * ACCELERATION not velocity but CHANGE in velocity/time
*October 2, 2014*

**Science**

F = m a = change in momentum/change in time (again) if there is no change in velocity there is no change in momentum and the net force on the bottle is zero so the forces are "balanced".
*October 2, 2014*

**physics**

|F| = sqrt (8.85^2 + 2.21^2) m = |F|/a = |F|/4.4
*October 2, 2014*

**Science**

F = m a =change of momentum/change in time so it accelerates, changes velocity
*October 2, 2014*

**physics**

a) m g h b) (1/2) m v^2 c) answer a - answer b = energy lost to friction energy lost to friction = work done by friction (friction force on tree *distance down) so friction force = energy lost/13 meters
*October 2, 2014*

**physics**

initial potential and total energy = E =m g h there is no friction in this problem so the total mechanical energy stays the same (1/2) m v^2 + m g h = E at every height h, you can calculate v
*October 2, 2014*

**Social Studies**

I believe that you are correct. I am sure that D is incorrect :)
*October 2, 2014*

**Physics**

10 min = 600 seconds 2,000 watts * 600 seconds = 1,200,000 Joules = 1.2*10^6 = 12 * 10^5
*October 2, 2014*

**Math Help!!**

In other words I think question 8 is missing the word "not".
*October 2, 2014*

**Math Help!!**

In number 8, B is the only one that is not a repeater https://www.google.com/search?q=repeating+decimal+definition&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a&channel=sb
*October 2, 2014*

**Math Help!!**

When in danger or in doubt, sketch the problem on a number line :)
*October 2, 2014*

**Math Help!!**

3. 7.2 x 12 x 0.23 = ? Round to the nearest hundredth. 19.872 since 2 is less than five, the nearest hundredth is 7 so 19.87 which is C as Brady said.
*October 2, 2014*

**Geometry**

(4/3)pi r^3 = 3,000 r^3 = 9000/(4 pi) r = [9000/(4 pi)]^(1/3) 4 pi r^2 = 4 pi [9000/(4 pi)]^(2/3)
*October 2, 2014*

**Science--3 questions? :c**

http://en.wikipedia.org/wiki/Nebular_hypothesis longitude altitude
*October 2, 2014*

**Science**

suspect you mean evolution on which case I would vote for a) with Darwin genetic adaptation http://grapes.msu.edu/integrated_pest_management/how_pesticide_resistance_develops
*October 2, 2014*

**Int. science**

I agree :)
*October 2, 2014*

**Int. science**

Oh, please guess !
*October 2, 2014*

**statistics**

I think you mean standard deviation of 9 http://davidmlane.com/hyperstat/z_table.html
*October 2, 2014*

**Distributive Property Algebra**

8(6 - 2) = 8(6) - 8(2) by distributive property of multipication = 48 - 16 = 32 --------------------------- You could also say 8*4 = 32 but that does NOT USE distributive property. ------------------------- 7 c + 7*4 by distributive property then = 7 c + 28
*October 2, 2014*

**science**

I am assuming that you are correct; the water evaporates
*October 2, 2014*

**physics**

That depends If you are in an car: If it is taking off from a stop light and accelerating forward then Thrust is greater than Drag If it is cruising along at constant velocity then Thrust forward equals drag back If you take your foot off the gas and coast then Thrust becomes ...
*October 2, 2014*

**physics**

drag is normally opposite to velocity.
*October 2, 2014*

**Algebra**

You are welcome.
*October 2, 2014*

**Algebra**

5m and 3 m are indeed like terms (combine like terms to make 8 m + 6 p + 4)
*October 2, 2014*

**Math**

(A) 2/5 (B) 2/5 = 24/60 (C) 2/5= what/35 multiply 2/5 by 7/7 and get 14/35 so 14
*October 2, 2014*

**Intro to Physical Science**

m g h = potential energy at top = 100 * 9.81 * 12 = 11,772 Joules loses 3550 Joules so (1/2) (100) v^2 = 11,772 - 3550 = 8222 Joules v = 12.8 m/s
*October 2, 2014*

**Math**

17 * 85/6
*October 2, 2014*

**n2 maths**

pi (25)^2/4 * 40 = n (4/3) pi (3)^3 6250 = 36 n
*October 2, 2014*

**math n2**

tan 58 = h/380
*October 2, 2014*

**physics**

d = .5 a t^2 a = 6/t .01 = .5 (6/t)t^2 = 3 t t = .00333 s F = change in momentum/change in time = .45 *6/.00333 = 810 Newtons
*October 1, 2014*

**physics**

10^3*10^8 = 10^11
*October 1, 2014*

**Physics**

h = (1/2) g t^2 in metric, g = 9.81 meters/s^2 in English g = 32 feet/second^2
*October 1, 2014*

**calc / physics**

yes yes
*October 1, 2014*

**Algebra**

- x^4 always - (-x)^4 always + x either -x either
*October 1, 2014*

**Math**

f(8+h) = sqrt (8+h) - 8 f(8) = sqrt(8) - 8 subtract sqrt (8+h) -sqrt (8) but d/dh (8+h)^.5 = .5 (8+h)^-.5 so sqrt (8+h) = sqrt 8 + .5 h/sqrt(8+h) subtract sqrt 8 .5 h/sqrt(8+h) divide by h .5/sqrt (8+h) let h -->0 .5/sqrt 8
*October 1, 2014*

**math**

x = [ -5 +/- sqrt(25 + 8) ]/4 = [ -5 +/- sqrt (33) ]/4
*October 1, 2014*

**physics**

a = change in velocity / change in time -.87 = change in velocity / 3.8 so change in velocity = -3.3 m/s
*October 1, 2014*

**Chem 400**

It is there 0.6548 g/mL *10^-3 mL/ uL =.6548 *10^-3 g/uL
*October 1, 2014*

**Chem 400**

hexane is 86 g/mol we have 55 uL *.6548 *10^-3 g/uL = 36*10^-3 g 36*10^-3/86 =4.2 * 10^-4 mol * 6*10^23 = 2.51*10^20 molecules of hexane now just add up the protons in a molecule and divide. It is C6H14 C has 6 each and H has 1 each
*October 1, 2014*

**math**

-50 3/4 = -203/4 = - 5075/100 -6.05 = -605/100 100 = 10,000/100 so (-5075 -605 + 10,000)/100 = 4320 / 100 = 43.2
*October 1, 2014*

**Printing press**

Good grief !!! Google Gutenburg
*October 1, 2014*

**Math**

8 j + 4 d = 64 4 j + 8 d = 92 multiply first eqn by 2 16 j + 8 d = 128 4 j + 8 d = 92 --------------- subtract 12 j = 36 j - 3 dollars per jump rope then d = 10 dollars per doll You can do it now
*October 1, 2014*

**math**

7 a + 3 s = 1625 s = 2 a so 7 a + 3 (2 a) = 1625 7 a + 6 a = 1625 13 a = 1625 a = 125 so s = 250
*October 1, 2014*

**Chemistry**

Huh ?? a mole of anything is about 6*10^23 of them like a dozen is 12 of something 2.65*10^15 ----------- 6 * 10^23 = .442 *10^-8 = 4.42 * 10^-9 moles
*October 1, 2014*

**Math**

546*714 /(42*42) = 221 but, is that exact? 546 / 42 = 13 714 / 42 = 17 yes, tiles do not have to be cut.
*October 1, 2014*

**math**

100 + 10(150 - 50)
*October 1, 2014*

**Math help!**

c - distributive d - commutative
*October 1, 2014*

**History**

I am no scholar of the period but am having trouble imagining the Italian cities working together to do this. Do you mean Venice and Genoa cooperating ?
*October 1, 2014*

**chemistry**

Xe = 131 g/mol F = 19 g/mol so XeFn = (131 + 19 n) g/mol or (131+19n)g / 6*10^23 molecules but this stuff is .368 g/9.03*10^20 molecules .368/9.03*10^20 = (131+19n) /6*10^23 131+19 n = 244.5 g/mol 19 n = 113.5 n = 6 so XeF6
*October 1, 2014*

**History**

That is just a symptom of the importance though. There is much more but I would have to write a book for you.
*October 1, 2014*

**History**

LOL gmta
*October 1, 2014*

**History**

What language do they speak there now?
*October 1, 2014*

**Math (for Damon)**

You are welcome :)
*October 1, 2014*