Wednesday
April 16, 2014

Posts by steve


Total # Posts: 21,692

Stats
Well, it must be immediately obvious that .9715 is bogus. A score of 10 is more than a whole SD below the mean, so there is no way that P(x<10) > 1/2 When I plugged in the data, I got P(x<10) = 0.1357 Still not one of your choices. However, the closest is 0.3, since y...

Physics
Oops. I just gave the mass of the seesaw on each side. That must be multiplied by the distance of its center of mass: 20(d/4.5)(d/2)+14*1.4 = 20(1 - d/4.5)((4.5-d)/2) + 39L

Physics
so, the mass of the seesaw can be ignored, since it is uniformly distributed. Now for the loads and their moments. They must balance on both sides, so 14*1.4 = 39*L Simple, no? Actually, since I have no diagram, I can't say that the seesaw mass may be ignored. If the pivot...

math
MTθF: 6/5 hr Sat: 4/5 hr W 1/5 hr 4 * 6/5 + 4/5 + 1/5 = 29/5 = 5 4/5 hr

math help
#2 is ok, but not yet complete: x^2-1 = (x-1)(x+1)

Math 20-3
v = 1/3 pi (3.4^2) (2.8) m^3

Algebra
If Literature, history and French are your life loves, then algebra probably will not be a great part of your life. But, life consists of a wide variety of experiences, and I guarantee you that some basic math know-how (yes, even including algebra) will make things easier. So,...

Algebra
Only you will know that. It's actually surprising how often basic math skills come in handy. Other than that, the mental skills developed when solving problems are definitely useful later in life, no matter the field of endeavor. Now, if you plan to find a sugar daddy/mama...

Algebra
well, 2(v-6) = 2v-12 Guess that's not it, eh? How about (v+4)(v-3) You need to find two numbers of opposite sign, which multiply to -12 and add up to +1. On the last one, (m^2 + 2m + 1/ m^3 + 3m^2 + 3m +1 (m^2/m - 3m/3) unless you can factor the polynomials, there's no...

Algebra
Just as in the previous two posts, you need to factor the trinomials and then cancel factors which occur in the top and bottom. Have you no ideas at all on factoring these? Or multiplying by the GCD to clear fractions?

Algebra
the GCD is x(x+3)(x+1), so if you clear fractions you get 3(x+3)(x+1) + 6(x)(x+1) = 8(x)(x+3) 3x^2+12x+9 + 6x^2+6x = 8x^2+24x x^2 - 6x + 9 = 0 (x-3)(x-3) = 0 x = 3

Algebra
r^2 + 6r +8 = (r+2)(r+4) So, what you have is (r^2-7r+12) / (r+4) * (r+2)(r+4) / (r^2-7r+12) Now lots of stuff cancels out and you are left with just (r+2)

Statistics
you can do lots of Z table stuff here: http://davidmlane.com/hyperstat/z_table.html

Algebra
Without actually checking, I'd have to say it better be yes. (Ohm's Law). Having said that, since amps*ohms is constant, 4y = .1*124 y = 3.1

algebra
The other root must be 4-i, so one factor is (x-(4+i))(x-(4-i)) = ((x-4)^2 + 1^2) = x^2-8x+17 So, now we have (x+3)(5x-1)(x^2-8x+17) at x=0, this is (3)(-1)(17) = -51, so y = -5/51 (x+3)(5x-1)(x^2-8x+17) = -5/51 (5x^4 - 26x^3 - 30x^2 + 262x - 51)

Maths
Well, if the sides are 5,4,4,4,3,3,3 you have the perimeter of 26 cm. So, you can build a nearly regular heptagon and just squash it till it has area 24 cm^2. Or, a trapezoid on the side of a rectangle might also do the trick.

Need 8 grade math help quick please!
there is only one number less than 2, and six possible throws. So, P(n<2) = 1/6 Similarly, P(n>=3) = P(n∊{3,4,5,6}) = 4/6 = 2/3 P(n≠4) = 1-P(n=4) = 1 - 1/6 = 5/6

Calculus
As a first check, I went to http://www.wolframalpha.com/input/?i=2%E2%88%AB[3%2C4]+%282%2F3+%E2%88%9A%28x^2-9%29%29+dx and saw that they show the area as 2.28 So, I suspect there is an error in the problem or the answer. Your calculation appears to be correct, within roundoff ...

Algebra word problem
C(x) is just a parabola, with minimum value at x = 1.2/0.2 = 6 so, 600 bikes will minimize the average cost per bike

math
we need <x,y> such that <x,y> + <6/√2,6/√2> = <0,-20> Now it's easy to get x and y, and thence the speed and direction.

Math
6 bags uses 5 pounds 12 bags uses 10 pounds, or 5 large bags.

3rd grade math
if there were x pieces to start, x/5 = 2 x = 10

Mathematics
T1 T2 = T1+1 T3 = T2+2 = T1+3 ... Tn = T1 + n(n+1)/2

math
change per year is (8750-23500)/8 = -1843.75 so, what's -1843.75/23500?

Math
a = 2pi*r(r+h) = 2pi*6*26 = 979.68 Hmmm. That includes both ends. The lateral area is a = 2pi*r*h = 2pi*6*20 = 753.6 Is there a typo somewhere? 2pi*6*24 = 904.3, so (D)

MATH HELP
If both lines go through (0,0), then one line has slope -2/3, so the other line has slope 3/2. so, s = 2/3

math
j=g j-2055 = g/4 = j/4 3/4 j = 2055 j = 2740

geometry
sinG/g = sinJ/j sinJ = sin(125)/63*36

geometry
B If two sides are a and b, the third side c must obey a-b < c < a+b because any side must be less than the sum of the other two.

math
recall that x^2-y^2 = (x-y)(x+y) so, substitute in x = a-b and y=c.

math
y = 3x-1 is probably the simplest, but it could also be y = 2x+7 y = 23 y = (1+∛x)^3 - 4 or lots of other possibilities. There are infinitely many relations which will take 8 to 23.

Geometry
given the three sides, with c being the largest, you know that the triangle is a right triangle if c^2 = a^2+b^2 if c^2 < a^2+b^2, then it's acute, and obtuse otherwise. So, start checking.

Math
(5+4-1)*3 = 24 (4-3+1)*12 = 24 (9-7)*(10+2) = 24

Math
4*4

Math
nope. You had to add 37x to both sides, so it should be y = 37x + 82

senior problem solving
x days from today, the number of ants n, is n = 350 * 2^(x/20) Now just plug in your values for n.

Calculus
y" = 5cos(t) so, when is that zero?

Calculus
-9.8 m/s^2

Stop the Madness!
I think part of the problem is that when a new question is posted, there is no list of related questions available to check. That only appears later when people open up the posting. And the search engine does not appear to be very good at providing relevant matches. And, most ...

Calculus
same as y": -cosx

trig
I meant 336.7°

trig
Assuming the normal 0° at North, and ignoring the misuse of the word "bearing", I'd say that the resultant heading of the plane is 246.7°

Geometry
not sure about your notation, but such a reflection takes (x,y) -> (-x,y)

Geometry
B Just add the components for X and Y

Calculus
The hands of a clock in some tower are 4.5m and 2m in length. How fast is the distance between the tips of the hands changing at 9:00 at time t hours after 12:00, (at t=0) the minute hand is at 4.5 sin(2pi*t) the hour hand is at 2.0sin(2pi*t/12) at 9:00, the distance d is d^2 ...

Calculus
Ahh. I see that I was interpreting 243^3/5 as (243^3)/5

Calculus
No one is bothered by the fact that 5 does not divide powers of 2 and 3?

Calculus
good except for this step: ln (243^3/5 *32^4/5) should be 1/5 ln (243^3 * 32^4)

math
If the balloon is between the stations h/x = tan45° h/(50-x) = tan60° h/tan45° = 50 - h/tan60° h = 50 - h/√3 h = 50/(1+1/√3) = 31.7 There is another answer if both stations are on the same side of the balloon.

pre calculus
C(x) = 2.00 for 0 < x <= 1 2.00 + .20(10x) for 1 < x < 2 since there are 10 charging units per mile.

physics
First you need to figure how much helium is the balloons. Each balloon's lift is reduced by the weight of the helium inside. Once you know how much each balloon weighs, subtract that from the lifting power of the displaced air, which is 1.225kg * .01716 * 9.8N/kg, since ea...

Math!!!!
this a line with slope -1/2 which goes through (0,-3) I think that should help some, eh?

Calculus
Since velocity is the derivative of position, v(t) = -32t + 160 now just solve -32t+160 = 32 -32t+128 = 0 t = 4

Math
yellow cards: 10 of 30 total so, P(y,y) = 10/30 * 9/29 = 3/29

math
r + .75(s-r) Just subtract r from s and add 3/4 of that to r.

math
If you mean (-8)^2 + (17 - 9)*4 + 7 = 64 + 8*4 + 7 = 103

Pre calculus
yes. The reason the law of sines can give two triangles is because sin(x) is positive all the way from 0 to 180. cos(x) becomes negative for x>90, so the formula takes that into account, always leaving only one possible answer. I mean, think about it geometrically. If you k...

irsc
as Galileo showed, it is the same for all objects (ignoring air resistance). Since F = ma, and a 20kg object weighs twice as much as a 10kg object, 2F = (2m)a but a remains the same.

Math
-1 13/14 = -1.9286 -1.9 = -1.9000 -1 9/11 = -1.8181 -1.95 = -1.9500 Now just order them, recalling that for negative numbers, greater means closer to zero.

Math
But -3.363636 < -3.333333

Math
x^2 + 4x + 4 = 0 (x+2)(x+2) = 0 the two solutions are -2 and -2, so their product is 4 In fact, for any quadratic ax^2 + bx + c = 0 the product of the solutions is c/a, so you don't even need to find what the roots are.

Geometry
2√((8-2)^2+(3+1)^2) = 14.4

Ms. Sue please help
Looks like you need to review how to find the slope of a line between two points: change.in.y divided by change.in.x and the point-slope form of a line. point (h,k) with slope m is y-k = m(x-h)

Ms. Sue please help
(-8, -4) and B (1, -5). slope is (-5+4)/(1+8) = -1/9 You must have had either +8 or -1 for x. #2) FG has slope (-5-7)/(-4-3) = 12/7 HI has slope (6-0)/(4+5) = 2/3 neither #3) GH has slope 4 you want slope -1/4, so y-3 = -1/4 (x-2) y = -1/4 x + 7/2 (D)

Math please ASAP
what about it? If both points have the same y-coordinate, the line is horizontal. Does not matter what the x-coordinate is. ALL points on the horizontal line y=3 are of the form (x,3) no matter what x is.

Math please ASAP
Since both have y=3, the slope is zero

integer Math
I guess they're just making sure you understand that all whole numbers are also integers.

integer Math
ummm, 52 52 IS a whole number typo?

math
5.5a + 4(200-a) = 980 solve for a to get # adults tickets subtract that from 200 to get # child tickets

Precalculus II
recall that sec^2 = 1+tan^2, so we have tan^2(x) + 3tan(x) - 4 = 0 (tan(x)+4)(tan(x)-1) = 0 tan(x) = 1 or -4 So, there will be 4 solutions, one in each quadrant.

math
differences: 5,10,15,20,25 so, the next difference ought to be 30, making the next term 111

math - great minds
what can I say?

math
sin 12πt has period 2π/12π = 1/6 cos 18πt has period 2π/18π = 1/9 So, the sum has period LCM(1/6,1/9) = 1/3 You can see this at http://www.wolframalpha.com/input/?i=10+sin%2812+pi+t%29%2B4+cos%2818+pi+t%29+

math
The room is 15x15 feet, making 225 sq ft. Each gallon covers 45 sq ft 5*45 = 225, so it will take 5 gallons. Or, as we solved it, 225/45 = 5

math
15*15/45 = 5

CHemistry
gotta work with moles. How many moles H2SO3 in 36.86g? Since each mole of H2SO3 requires 1 mole of SO2, you need the same number of moles. So, convert back to g of SO2

physics
not sure just what you're after, but current in a conductor can cause it to heat, changing the resistance. Ohm's Law says I = E/R, and assumes a constant value for R. Heating may alter this, though at any instant the relation still holds, if the changing R is taken int...

Math
(x,y) -> (x+8,y-2)

Geometry
(A) is just PQR (B) is PQR reflected in the line y=0 (C) is PQR rotated 180° about (0,0) or, reflected twice, across both axes (D) is PQR reflected in the line x=0 Not sure what your notation is supposed to indicate.

Math
well shucks -- us farm boys know that 1 sq mile is 640 acres.

Math
so, we need to divide each tier into 1" square pieces. we need a^2+b^2+c^2 >= 300 6^2 = 36 8^2 = 64 10^2 = 100 12^2 = 144 14^2 = 196 16^2 = 256 a b c sum 6 8 10 200 6 8 12 244 6 8 14 296 6 8 16 356 8 10 12 308 That's it. Any other combination will be way over 308 s...

geometry
if you want integer dimensions, then since 28 = 2^2 x 7 the mold must be 2x2x7 or 1x1x28

Algebra - incomplete
unless you show the inequality, don't expect any help.

Math
After winning 8 games (of 10) their % rose from 60% to 65%. So, .60n + 8 = .65(n+10) n = 30 So, they played 40 games altogether. check: 60% of 30 = 18 18+8=26 is 65% of 40

math
well 63/7 = 9 49/7 = 7, so 9.07

pre calculus
-1 - 1/√3

Math
if the distance AP = x, the total distance flown is d = √(1+x^2) + (2-x) where x<2. If flying over land requires 1 unit of energy, then the energy cost is c = 10/9 √(1+x^2) + 1(2-x) Now just find the minimum of c.

calcules
I assume that C is the point on shore closest to B. So, if the pipeline leaves the shore at point P, between A and C, and the distance PC = x, the length p of the pipeline is p(x) = (7-x) + √(x^2+36) now we see that the cost c of the pipeline is c(x) = 400(7-x) + 500W...

Physics
6.0 N = (0.00,6.00) 4.0 NE = (2.83,2.83) 2.0 N25E = (0.85,1.81) 4.0 E = (4.00,0.00) Now just add 'em up and convert back to distance and heading

Pre Algebra
what figure has 3 lateral faces that are rectangales

Pre Algebra
I'd say yes, since a rectangle and a triangle can be combined to make a trapezoid. But not always; the triangle must meet certain conditions.

Pre Algebra
CAN A TRIANGULAR PRISM PLUS A RECTANGULAR PRISM MALKE A TRAPAZOIDAL PRISIM

Pre Algebra
can a trapezoiodal prism equal a triangular prism and rectangular prism combined

algebra
the solution set to an inequality is not just a number, but a whole range of numbers which satisfy the inequality. Any x between 2 and 4 is a solution to this problem, as well as in the other intervals. Graphed on the number line, we have http://www.wolframalpha.com/input/?i=s...

algebra
you need to solve two inequalities: x(40-2x)(25-2x) > 1512 x(40-2x)(25-2x) < 2176 x(40-2x)(25-2x) = 4x^3 - 130x^2 + 1000x So, you have to solve 4x^3 - 130x^2 + 1000x - 1512 > 0 4x^3 - 130x^2 + 1000x - 2176 < 0 a little synthetic division shows that the first has a ...

Calculus - good catch bob
Dang - forgot the restriction on the domain.

Calculus
the number of apples is yield/tree * # trees. With x trees, yield per tree is 200 - 5(x-50) for x > 50 So, total crop is c(x) = x(200-5(x-50)) = x(450-5x) = 450x - 5x^2 c'(x) = 450-10x c' = 0 at x=45 So, the max yield is achieved with 45 trees

Grade 12 Calculus
if the sheet is x by y, and is rolled along the y axis, 2x+2y = 100 v = pi r^2 y where 2pi r = x, or r = x/(2pi), so v = pi (x/(2pi))^2 (100-2x)/2 = x^2(50-x)/(4pi) dv/dx = x(100-3x)/(4pi) dv/dx=0 when x = 100/3 at that point, max v is pi*(50/3)^3

Pre Algebra
thank you

Pre Algebra
What figure has exactly 4 lateral faces that are triangles?

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