Friday
August 22, 2014

Posts by STEVE


Total # Posts: 24,377

Math
Add up all the numbers: 632 There are 12 numbers, so the mean is 52.666 Now, you want to remove one value so that the remaining 11 have a mean of 56.09. Well, 11*56.09 = 617 So, if you remove one of the 15's, the remaining 11 numbers add up to 617, giving the desired mean.
June 20, 2014

Pre-Calculus
You show that it is true for n=1. Then you show that if it is true for n=k, then it must also be true for n=k+1. That means that the assertion is true for all values of n, starting with n=1, and thus for n=2,3,4,... For instance, a common proof is that the sum of the first n ...
June 20, 2014

Math
to lower the mean, remove the highest scores. To raise the mean, remove the lowest scores.
June 20, 2014

finite Math
17000 * 1.04^5
June 20, 2014

physics
same seat assuming that the windows are closed...
June 20, 2014

math
63 divided by (10-3) + 2 x 4 = 63/7 + 8 = 9+8 = 17 However, (63/7 + 2)x4 = (9+2)x4 = 11x4 = 44 Normally multiplication is done before addition
June 20, 2014

math
8*600 = 4800 radios produced. That leaves 2800 more to be done in 4 days. I think probably you can take it from there.
June 20, 2014

Math
I generally don't think of circles as having ends, so maybe the fence is rectangular or square. However, since you talk about using pi=22/7, I'll assume you want a circular fence, and the diameter is 10 ft. So, C = 10pi = 31.4 ft $440/31.4ft = $14.01/ft
June 20, 2014

algebra
first place is to check your text for some kind of distance formula. Next, get out some graph paper and plot the two points, then draw a line between them. Call them A and B, respectively. Now draw a horizontal line from A and a vertical line from B. Where the two lines ...
June 20, 2014

physics
if the velocity changes from 25m/s to 0 in 5 seconds, that's an acceleration of -5m/s^2. So, the distance covered till the full stop is 25*5 + 25t + 1/2 (-5)t^2 with t=5, that's 25*5 + 25*5 - 125/2 = 187.5 m
June 20, 2014

Math
when (1/2)^(t/60) = .05 t/60 = log.05/log.5 t = 259.3 days
June 19, 2014

chemistry
HCl + NaOH -> NaCl + H2O each mole of NaOH reacts with one mole of HCl. so, how many moles of NaOH in 40g? How many grams of HCl in that many moles?
June 19, 2014

Math
25x^2 - 30x = -9 25x^2 - 30x + 9 = 0 (5x-3)(5x-3) = 0 ...
June 19, 2014

Algebra
mathematically, |b| ≠ 2 or b^2 ≠ 4
June 19, 2014

physics
on the ground, the weight is mg = 100*9.8 = 980N Now, g=9.8 because F = GMm/r^2 = mg, so g = GM/r^2 If we say that r=6371km, then at 1000km altitude, we will have 9.8 * (6371/7371)^2 = 7.32, so the 100kg mass will weigh only 732N
June 19, 2014

Algebra direction how to do it
As you know, y = 4x-4 is just a line. All the points on the line satisfy the equation. > means "greater than". So, if (2,4) is on the line, (2,5),(2,6),... are above the line, where y > 4x-4. So, the solution to an inequality is a whole region of the plane, not...
June 19, 2014

Algebra
1 - x^2/x = 1-x (1-x^2)/x = 1/x - x (2b-2)/(2b^2-8) = (b-1)/(b^2-4) = (b-1) / (b-2)(b+2) Not sure just what you're after
June 19, 2014

math
since a = bh/2, we have a = 14x/2 = 7x so, 7x <= 112 x <= 16
June 19, 2014

College Alegbra
(a) d(j(x)) = .75(j(x)) = .75(x-5) (b) j(d(x)) = d(x)-5 = .75x - 5 (c) go for it
June 19, 2014

algerbra
the difference between three-fifths and five is equal to the product of x and the sum of y and seven. Seems kinda dumb. Why all the nonsense with 3/5 - 5?
June 19, 2014

math
55+25-15 = ?
June 19, 2014

geometry
time to draw a diagram and review your basic trig functions: DE/10 = tan 25° It also helps to recall the alternate interior angles between parallel lines are equal.
June 19, 2014

algebra
well, you need a 1, so that would be 3/3 Now you need 30 more, using three 3's. Looks like 3^3 + 3 + 3/3
June 19, 2014

Math
a.bc a > 0 b = a+1 c = a+b 1.23, 2.35, 3.47, 4.59 Unless there are further conditions, just pick one.
June 19, 2014

math
Well, the roots are -1/2 and 1, so I hope some of the choices were near those values.
June 19, 2014

math
each of 5 people plays 4 others. That's 5*4 But, that counts each person twice, so you really have 5*4/2 = 10 games
June 19, 2014

math
all correct good work
June 19, 2014

algebra
If you mean 2y/3 + 2y - 6/15 then that is just 2y/3 + 6y/3 - 6/15 = 8y/3 - 2/5 = (40y-6)/15 If that's not it, then use some parentheses and show your own work.
June 19, 2014

Math
well, you have ax^2 = -h ax^2 = h In either case, a and h must have the same sign, since x^2 is always positive. Unless x=0, in which case, h=0. x = ±√|h/a| Naturally, if a=0, there is no solution unless h is also zero.
June 19, 2014

math
looks like you need to review your basic triangles: sin 60°/cos^2 45° - cot 30° + 15cos 90° √3/2 / 1/2 - √3 + 15*0 √3 - √3 0
June 19, 2014

Math
You have calculated the number of feet in 26 miles. Now divide that by (32/12), the number of feet in one stride. Or, you can multiply 137280 by 12 to get the number of inches in 26 miles, and then divide that by 32, the number of inches in one stride. Same difference.
June 19, 2014

Trigonometry
secx - √2 = 0 secx = √2 x = π/4 If this gave you trouble, it looks like you need to review your basic trig functions and common triangles.
June 19, 2014

algebra
x+y = 15000 .08x + .07y = 1100 Now just solve for x at 8% and y at 7%
June 18, 2014

Physics
(30,0) + (9.64,-11.50) = (39.64,-11.50) √(39.64^2 + 11.50^2) = 41.27 tanθ = -11.50/39.64
June 18, 2014

Math
750000 * 0.8^3 at the start of the 4th year. 750000 * 0.8^4 at the end of the 4th year you will have to decide when "during" the year you want its value.
June 18, 2014

Math
sinθ = 10/15
June 18, 2014

Math
(1*1 + 5*2 + 3*5 + 1*10 + 1*100) ------------------------------------ (1+5+3+1+1)
June 18, 2014

finite math
(# left field) / (# hits) = 6/59
June 18, 2014

math
Clearly, attendance on M-W is 33,34,35 So, attendance on Th-Sat is 36,37,38 with average=37
June 18, 2014

algebra
think 3-4-5 right triangle. or, do the math: √(50^2 - 30^2)
June 18, 2014

Math
481,924,821,947,217,481,274,832,748,971,298
June 18, 2014

math - ouch
Dang. Don't know what I was thinking.
June 18, 2014

math
what's the trouble? Just start working in the clues. The number is 2.abcdefg... c = a+b b = c-a (well, duh) b = c-1 It appears that the number is just 2.abc c = a+c-1 a = 2c+1 Now, since a < 10, c < 5 So, if a = 0,1,2,3,4 then c = 1,3,5,7,9 and b = 1,2,3,4,5 So, we ...
June 18, 2014

Algebra 1
the slope of the line is positive, so maximum y will occur where the maximum x occurs. So, y <= 5 Since lines extend to infinity, the range is thus (-∞,5]
June 18, 2014

math
The 48 is just noise. The cost (c) of the tickets for p pupils is c = 150p 150*43 = 6,450 So, the figure of 6,350 is incorrect. Whether or not it is wrong for the teacher to say otherwise is a moral question ...
June 18, 2014

math
1/(1+√2+√3) * 1/(1-(√2+√3))/(1-(√2+√3)) = (1-√2-√3)/(1 - (√2+√3)^2) = (1-√2-√3)/(-4-2√6) = (1-√2-√3)/(-2(2+√6)) = (1-√2-√3)/(-2(2+√6)) * (2-√6)/(2-√6...
June 18, 2014

Math
yes each value of x produces a distinct value of y.
June 18, 2014

Math
yes no maybe
June 18, 2014

math
If those "x" signs mean multiplication, then you surely know that 0x anything is zero.
June 18, 2014

math
n(n-1)/2 = 171 Since 342 = 18*19, there were 19 teachers.
June 18, 2014

physics
g = GM/r^2 at r+h, g1 = GM/(r+h)^2 at r-x, g2 = GM/(r-x)62 ∆g = GM(1/(r-x)^2 - 1/(r+h)^2) = GM/((r-x)^2(r+h)^2) ((r+h)^2-(r-x)^2) = GM/((r-x)^2(r+h)^2) (2rh+h^2 - 2rx+x^2) Since r-x and r+h are both approximately r, we have ∆g = GM/r^4 (2r(h-x) + h^2+r^2) = 2GM/r^3...
June 18, 2014

finite mate
anythingP0 = 1 There is only 1 way to choose nothing.
June 17, 2014

Algebra
You can factor out a^2 b, giving a^2 b (a^2 + b^2) Not sure that's any simpler.
June 17, 2014

Math
multiply RS top and bottom by cos2x and you have 2/(1-cos2x) = 2/(1-(cos^2 x - sin^2 x)) = 2/(1-cos^2 x + sin^2x) = 2/(2sin^2 x) = 1/sin^2 x = csc^2 x
June 17, 2014

Algebra
you want two factors of 45 which add to 18. Since 45 = 15*3, you get (x+15)(z+3)
June 17, 2014

math
y = 6x+4 Since you know the number of games, and the cost depends on that, x is the independent variable.
June 17, 2014

math
Arrange the coefficients into a 3x3 matrix, filling in zeros for missing values. A matrix is in row echelon form if (1) All nonzero rows (rows with at least one nonzero element) are above any rows of all zeroes (if any). (2) The leading coefficient of a nonzero row is always ...
June 17, 2014

Algebra/please can some one help I forgot
Just look up the formula for monthly payment of loan amortization, and plug in your numbers.
June 17, 2014

MATH
no problem. Literally -- no problem. All you have done is give us the definition of some set of BOYs.
June 17, 2014

geometry
C = 3.14 * 60 = 188.4 cm 33.3 rpm means the bicycle travels 33.3 * 188.4 cm in one minute.
June 17, 2014

geometry
360 degrees is just one revolution. So, in 48 minutes, it turns 48 times. By the way, most LPs rotate at 33 1/3 rpm, not just 1 rpm. Also, they don't play for any 48 minutes either. Stupid question.
June 17, 2014

geometry - oops
I misread 1008 as 1080. Go with Reiny.
June 17, 2014

geometry
720 = 2^4 * 3^2 * 5 1080 = 2^3 * 3^3 * 5 672 = 2^5 * 3 * 7 So, the largest number that evenly divides all of those is 2^3 * 3 = 24
June 17, 2014

algebra
x+y=15 8x+5y=96 now just solve for x and y
June 17, 2014

Math
150 is less than the mean for Natalia's class. So, if that score is removed, the mean rises. Similarly, since 150 is greater than the mean for Eric's class, if that score is added, the mean rises.
June 17, 2014

Math
y = x^2 + 3x + 1/4 = x^2 + 3x + (3/2)^2 + 1/4 - (3/2)^2 = (x + 3/2)^2 - 2 That should answer most of your questions.
June 17, 2014

Math
30x+20y+10z = 800000 x+y+z = 40000 x = y/2 x=10,000 y=20,000 z=10,000
June 17, 2014

algebra 1
If we model the situation as y = mx+b then we have 120m+b = 18 300m+b = 6 Subtract to get -180m = 12 m = -1/15 So, b = 26 y = -1/15 x + 26 y=0 when x = 390
June 17, 2014

finite math
Hmm. Looks like 0.438
June 17, 2014

finite math - PS
That's the experimental probability. The theoretical probability is still 1/2.
June 17, 2014

finite math (probability
I'd say 57/100
June 17, 2014

math
400m+b = 2150 300m+b = 1650 subtract to get 100m = 500 m = 5 so, b = 150 y = 5x+150
June 17, 2014

physics
given the drawing as shown below, I calculate 3.62 km at 46°
June 17, 2014

geometry
Assuming the chords are parallel, think of 8-15-17 right triangles.
June 17, 2014

Science
Seems to me that the only possible reason can be that ice provides less friction, whatever the underlying properties. Friction translates into a restraining force, reducing the speed.
June 17, 2014

science
F = ma, so 20 = 4m m = 5 kg
June 17, 2014

math
what a lot of noise. Distance traveled: 128100 ft = 24.26 mi Average speed: 335.92 mi/hr so, time falling is 24.26mi / 335.92mi/hr = 0.0722hr = 4.3 minutes
June 17, 2014

chemistry
1000cm^3 * 13.6g/cm^3 * 1mole/200.59g = 67.8 moles
June 17, 2014

chemistry
.09g * 1mole/18g * 6.02*10^23mol/mole = 3.01*10^21 molecules
June 17, 2014

chemistry
just plug in the mol wts of the compounds in 0.78*N2 + 0.21*O2 + 0.009*Ar * 0.001*CO2
June 17, 2014

algebra
the ratio is 6:6, making 12 total. 48 = 12*4, so 24:24 will satisfy everyone.
June 17, 2014

Geometry
figure the length and slope of AB and CD. If they match, it's a ||-ogram.
June 16, 2014

Geometry
well, what are the diagonals? AC and BD midpoint of AC = (-1/2,-2) midpoint of BD = (-1/2,-2) Looks like the diagonals bisect each other.
June 16, 2014

projectile motion
we know that the path follows x(t) = v cosθ t y(t) = 160 + v sinθ t - 4.9t^2 I will assume that the cliff and the tower are the same, otherwise I'm confused. x(20) = 1800 y(20) = 0 So, 20v cosθ = 1800 20v sinθ = 1800 Clearly θ = π/4 and v = ...
June 16, 2014

Algebra
no solution the lines are parallel, and so do not intersect.
June 16, 2014

Algebra
see the solution at http://www.wolframalpha.com/input/?i=solve+4y%3Dx%2B4%2C+x%3D2%2F3y%2B8%2F3+
June 16, 2014

Physics
150km/2.5hr = 60km/hr 150km/2.0hr = 75km/hr velocities is the same, but directed. 300km/4.5hr = 66.67km/hr avg velocity is 0, since no net distance was traveled.
June 16, 2014

Physics
4 hr * 300km/hr = 1200km 2.5 hr * 400km/hr = 1000km 2200km/6.5hr = 338.46km/hr
June 16, 2014

Math: Trig
since cos pi/3 = 1/2, sec pi/3 = 2 But, arcsec has principal values from 0 to pi, so arcsec(-2) = pi - pi/3 = 2pi/3. Note: Some authors define the range of arcsecant to be ( 0 ≤ x < π/2 or π ≤ x < 3π/2 ), because the tangent function is ...
June 16, 2014

MATH
No idea. Do it the way I did, but you have to use integration by parts. If you get stuck, show how far you got. You should wind up with -(x+1)e^-x for x<0 (x-1)e^x for x>=0
June 16, 2014

MATH
since |x| = -x for x < 0. ∫[-∞,x] e^-|t| dt = ∫[-∞,x] e^t dt if x < 0 = e^t So, for x>=0, ∫[-∞,x] e^-|t| dt = ∫[-∞,0] e^t dt + ∫[0,x] e^-t dt = 1 + (1-e^-x) = 2 - e^-x
June 16, 2014

maths
32 is 2^5 so, 1/32 = 1/2^5 = 2^-5
June 16, 2014

Math - incomplete
did you want some particular value for x?
June 16, 2014

Calculus
Note that you have ∫1/(x^2 − 2x + 8)^(3/2) dx = ∫1/((x-1)^2 + 7)^(3/2) dx If x-1 = √7 tanu (x-1)^2 + 7 = 7 sec^2 u dx = √7 sec^2 u du and you have ∫1/(√7 secu)^3 * √7 sec^2 u du = ∫ 1/7 cosu du = 1/7 sinu = 1/(7 csc u) = 1...
June 16, 2014

pseudocode app
this kind of code is about as simple as it gets. I don't know what language you plan to use, but do a little google to see how others have performed the operations you desire. There are lots of code snippets on line.
June 16, 2014

pseudocode app
read price tax = price * 0.08 print price,tax
June 16, 2014

Dela ray Mkhatshwa j.s.s
Let AC and BD intersect at E. Note that AE = 3 Draw a vertical line which will contain AC. Mark point E by intersecting an arc of radius 3 from A to E. Construct the perpendicular at E to AC. That will contain BD. Draw an arc centered at A of radius 6, which will intersect the...
June 16, 2014

Arithmetic
since the ratio between terms is constant, (k+6)/(2k+3) = k/(k+6) (k+6)^2 = k(2k+3) k^2+12k+36 = 2k^2+3k k^2 - 9k - 36 = 0 (k-12)(k+3) = 0 k = 12 and the sequence is 27,18,12,... so the ratio is 2/3 and S = 27/(1/3) = 81
June 16, 2014

Science
you need 4m = 600
June 16, 2014

sci
ever been on a roller coaster? ever stuck your finger in a wall outlet?
June 16, 2014

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